The DOI matches its Crossref record; 58 of the 58 references it cites were found in a registry or an index; 2 of the 34 sources its claims cite were checked for support.
The hormonal regulation of axillary bud growth in Arabidopsis
Open accessAbstract
Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger. Candidates include the plant hormones ethylene, cytokinin and abscisic acid. We have developed a new assay to study this phenomenon using the model plant Arabidopsis. The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections. We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond. We have used the assay with nodes from wild-type and hormone-signalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin. Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition. Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it. By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition. These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin. However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.
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65 Own result · 14 No full text of the sources · 14 Own interpretation · 7 Own method · 2 Supported so far · 2 Not checked yet · 1 Sources not found
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In the paper
“auxin levels in the bud actually increase as lateral buds begin to enlarge and grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Introduction
What the sources say
- Supportedcites Gocal et al., 1991 source
The Discussion reports that IAA concentration increased fivefold in the larger axillary bud within four hours of decapitation. It also reports increased bud size and fresh weight by eight hours, closely associating the IAA increase with the onset of growth. (LLM, conf=0.93)
- Not matchedcites Hillman, 1984
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not checked — no full text of the sourcecites Pearce et al., 1995 source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Supported
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, despite the lower growth rates, inhibition by apical 1 mM NAA was clearly demonstrated with both etr1 and AVG treatments.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: The etr1 mutant is ethylene-insensitive.
- Rests on an assumption: AVG inhibits ethylene biosynthesis.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“NAA at this concentration (10 mM) could also inhibit outgrowth from longer buds, up to 3.5 mm long at excision (data not shown).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When both hormones were applied basally, bud growth was similar to that of untreated controls.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of cytokinin
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“although basally applied abscisic can enhance inhibition by apical auxin”
- Also stated in: § The effect of ethylene and ABA on auxin-mediated inhibition · plain
“Combining basal 3 mM ABA with apical 1 mM NAA increased the duration of inhibition signi®cantly compared with apical NAA alone.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Abstract Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger.Candidates include the plant hormones ethylene, cytokinin and abscisic acid.We have developed a new assay to study this phenomenon using the model plant Arabidopsis.The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections.We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond.We have used the assay with nodes from wild-type and hormonesignalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin.Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition.Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it.By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition.These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin.However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Also stated in: § The effect of ethylene and ABA on auxin-mediated inhibition · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“If 1 mM NAA was supplied both apically and basally simultaneously, the mean duration of inhibition, compared to apical NAA alone, was increased from 5 days to 7±8 days.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“basally applied cytokinin was found to release lateral buds from inhibition by apical auxin”
- Also stated in: § The effect of cytokinin · plain
“Basal 1 mM BA was found to release the inhibition of outgrowth by 1 mM apical auxin in most instances.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Abstract Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger.Candidates include the plant hormones ethylene, cytokinin and abscisic acid.We have developed a new assay to study this phenomenon using the model plant Arabidopsis.The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections.We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond.We have used the assay with nodes from wild-type and hormonesignalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin.Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition.Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it.By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition.These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin.However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Also stated in: § The effect of cytokinin · plain
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Buds exposed to combined apical NAA plus BA were also more resistant to release by basal BA than buds exposed to apical NAA alone (data not shown).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of cytokinin
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, dye supplied in the apical media block did not appear in the leaf or bud.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“NAA at a concentration of 10 mM supplied to both ends completely inhibited all outgrowth of the lateral shoots for the duration of the experiment (14 days).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- It may state two separate claims as one. 33
- Probably not a substantial claim. 12
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
What the sources say
- Supportedcites Gocal et al., 1991 source
The Discussion reports a fivefold increase in IAA in the larger axillary bud within four hours of decapitation. It says this increase was closely associated with the bud’s release from arrested development and subsequent growth. Gocal et al. is cited for the auxin-level clause, not the separate polar-transport clause. (LLM, conf=0.93)
- Not checked — no full text of the sourcecites Morris and Johnson, 1990 source
- Not checked — no full text of the sourcecites Morris, 1977 source
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Supported
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When the orientation of the hormones was reversed, i.e.NAA basally and BA apically, the mean rate of lateral outgrowth was the same as the controls for the ®rst 120 h, after which the buds from this treatment tended to die.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of cytokinin
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Basal 1 mM BA caused a slight increase in the rate of lateral growth, such that buds were on average one-third longer than controls after 72 h.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of cytokinin
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When abi1-1 was tested, it was found that the buds were completely insensitive to ABA in any orientation and auxin inhibition was unaffected (Figure 5d).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Rests on an assumption: The abi1-1 and abi2-1 mutants are ABA-insensitive.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In fact, inhibition by apical 1 mM NAA was more prolonged when combined with either AVG or etr1 in the assay (24 h longer, on average, with AVG and 5±6 days longer with etr1).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Rests on an assumption: The etr1 mutant is ethylene-insensitive.
- Rests on an assumption: AVG inhibits ethylene biosynthesis.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Concentrations of apical NAA higher than 1 mM prolonged the period of inhibition, with 10 mM inhibiting most buds for at least 7 days and many for the duration of the experiment: 10±14 days (Figure 3b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Buds larger than 1.5 mm at excision of the nodal section were increasingly less likely to be inhibited by 1 mM NAA for any period, and most lateral buds greater than 3 mm in length grew out at rates not signi®cantly different from control buds.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“By contrast, when apical 2,4-D was used, the buds were completely inhibited for 2± 10 days and when growth began it proceeded at a greatly reduced rate.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“It was found that Landsberg erecta appeared generally more sensitive to ABA than Columbia.In Landsberg, the rate of bud outgrowth was dramatically reduced (and to approximately the same degree) by 3 mM ABA in any orientation”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“When the polar transport inhibitor 1-N-naphthylphthalamic acid (NPA) was supplied apically (1 mM), inhibition by 1 mM apical NAA was partially relieved (Figure 4b).”
- Also stated in: § Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown). · plain
“Supplying apical NPA prevented inhibition by apical NAA.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of NPA on auxin-mediated inhibition
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- Also stated in: § Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown). · plain
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In the paper
“Basal and apical 3 mM ABA did not affect the rate of bud outgrowth signi®cantly, but, when supplied in both media blocks, a slight reduction in growth rate was observed.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
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In the paper
“The rate of lateral outgrowth in the etr1 mutant was slower than in wild-type, and 5 mM AVG, supplied in both media blocks, also reduced the rate of bud growth substantially.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
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- Rests on an assumption: The etr1 mutant is ethylene-insensitive.
- Rests on an assumption: AVG inhibits ethylene biosynthesis.
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In the paper
“Apical 0.5 mM NAA inhibited the outgrowth of many buds, but usually for a shorter period than 1 mM NAA, and apical 0.1 mM NAA did not affect the rate of bud growth (Figure 3b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
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In the paper
“Even with the orientation of the nodes reversed, NAA supplied at the inverted apical end was found to inhibit outgrowth, but still had no effect when provided at the basal end (data not shown).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
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In the paper
“Apical cytokinin and cytokinin applied to both sides had little effect.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of cytokinin
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In the paper
“IAA at a concentration of 1 mM prevented outgrowth for 2±4 days and was similar in effect to 0.5 mM NAA.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
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In the paper
“The most prevalent natural auxin, IAA, and the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) supplied apically were also able to inhibit bud outgrowth (Figure 3c).Apical IAA was found to be a less potent inhibitor than NAA.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
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In the paper
“In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“Growth of lateral shoots from excised node 1 was slow for the ®rst 24 h (0±1 mm).The growth rate then increased steadily to settle at an average of 7 mm per day between 72 and 144 h (Figure 2).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
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In the paper
“Apical NPA can release auxin inhibition of bud outgrowth, but basal NPA cannot (b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Set-up and measurements
plaindirectn = 10- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
- Rests on an assumption: The excised nodal section assay reproduces the hormonal regulation of axillary bud growth in intact Arabidopsis plants.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The cytokinin BA, when applied basally, apically or both, had relatively little effect on the outgrowth of the lateral buds in the assay, although a small stimulation of the rate of growth was seen when 1 mM BA was added basally.”
- Also stated in: § Set-up and measurements · hedged
“When supplied alone, BA generally has little effect on the rate of bud outgrowth (a), but when supplied basally or apically with apical NAA, BA can, respectively, release or enhance inhibition of lateral bud outgrowth (b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of cytokinin
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- Also stated in: § Set-up and measurements · hedged
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In the paper
“Small buds are more sensitive to apical auxin than large buds, which become essentially unresponsive to the hormone.”
- Also stated in: § Set-up and measurements · plain
“Buds longer than 1.5 mm at excision become unresponsive to inhibition by 1 mM NAA (a).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Conclusion
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It may state two separate claims as one.
- Rests on an assumption: The excised nodal section assay reproduces the hormonal regulation of axillary bud growth in intact Arabidopsis plants.
- Also stated in: § Set-up and measurements · plain
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In the paper
“Apical ABA can reduce auxinmediated inhibition, whilst basal ABA enhances it.”
- Also stated in: § Set-up and measurements · plain
“When combined with apical 1 mM NAA, the ABA enhances inhibition when supplied basally, reduces it when supplied apically, and has little effect when supplied to both sides (c).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of abscisic acid
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It may state two separate claims as one.
- Rests on an assumption: The hormone concentrations used in the assay (e.g., 1 mM NAA, 3 mM ABA) are within a physiological range and their effects reflect natural hormonal roles.
- Also stated in: § Set-up and measurements · plain
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In the paper
“It was also noted that buds on nodal sections from the Landsberg erecta ecotype grew out more slowly than those of Columbia, and hence the difference between auxin-treated and control buds is reduced.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of ethylene and ABA on auxin-mediated inhibition
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
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In the paper
“The growth curve for lateral buds from node 1 on intact Columbia plants grown in sterile culture, under the same light and temperature regimes, was more linear than for the excised nodes (Figure 2).Initially growth rates were similar, but although the growth rate of lateral shoots on excised nodes accelerated after 72 h, the comparative growth of lateral shoots on intact plants was signi®cantly Sl”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Growth of excised buds
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Abstract Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger.Candidates include the plant hormones ethylene, cytokinin and abscisic acid.We have developed a new assay to study this phenomenon using the model plant Arabidopsis.The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections.We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond.We have used the assay with nodes from wild-type and hormonesignalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin.Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition.Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it.By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition.These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin.However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.
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Probably not a substantial claim.
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In the paper
“Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition.”
- Also stated in: § The effect of ethylene and ABA on auxin-mediated inhibition · plain
“Hence ethylene biosynthesis and ethylene action do not mediate auxin inhibition of lateral bud growth.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Abstract Apically derived auxin has long been known to inhibit lateral bud growth, but since it appears not to enter the bud, it has been proposed that its inhibitory effect is mediated by a second messenger.Candidates include the plant hormones ethylene, cytokinin and abscisic acid.We have developed a new assay to study this phenomenon using the model plant Arabidopsis.The assay allows study of the effects of both apical and basal hormone applications on the growth of buds on excised nodal sections.We have shown that apical auxin can inhibit the growth of small buds, but larger buds were found to have lost competence to respond.We have used the assay with nodes from wild-type and hormonesignalling mutants to test the role of ethylene, cytokinin and abscisic acid in bud inhibition by apical auxin.Our data eliminate ethylene as a second messenger for auxin-mediated bud inhibition.Similarly, abscisic acid signalling is not to be required for auxin action, although basally applied abscisic can enhance inhibition by apical auxin and apically applied abscisic acid can reduce it.By contrast, basally applied cytokinin was found to release lateral buds from inhibition by apical auxin, while apically applied cytokinin dramatically increased the duration of inhibition.These results are consistent with cytokinin acting independently to regulate bud growth, rather than as a second messenger for auxin.However, in the absence of cytokinin-signalling mutants, a role for cytokinin as a second messenger for auxin cannot be ruled out.
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It may state two separate claims as one.
- Rests on an assumption: The etr1 mutant is ethylene-insensitive.
- Rests on an assumption: AVG inhibits ethylene biosynthesis.
- Also stated in: § The effect of ethylene and ABA on auxin-mediated inhibition · plain
In the paper
“The export of cytokinins from roots has been shown to be in¯uenced by apical auxin, and this has led to the hypothesis that inhibition by apical auxin is mediated wholly or partly by its in¯uence on cytokinin export from the roots (Bangerth, 1994).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of cytokinin
What the sources say
- Not checked — no full text of the sourcecites Bangerth, 1994 source
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
What the sources say
- Not checked — no full text of the sourcecites Wickson and Thimann (1958) source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The assay we have developed allows various combinations of plant hormones and/or phytotropins and/or metabolic inhibitors to be supplied to each side of the node separately.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Discussion
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth Our data show a direct relationship between the concentration of apical auxin and the duration of the inhibition of bud outgrowth (Figure 3).Other workers have found that increasing the concentration of auxin applied to the cut stump of decapitated plants (Thimann, 1937;Went, 1939), or to the apical end of explants (Tamas et al., 1989), decreases the ®nal length of lateral buds.Wickson and Thimann (1958) observed that buds on nodal sections of Pisum sativum immersed in nutrient solutions were inhibited for approximately the same period over a range of IAA concentrations.The buds would `breakaway' after 5 days, but their subsequent growth was slower at higher IAA concentrations.In contrast, we have found that, when apical NAA is applied, the time to breakaway increases as the concentration is raised from 0.1 to 10 mM, often with little difference in the subsequent rate of outgrowth (Figure 3b).The mechanism behind this concentrationdependent timing of breakaway is unclear.A decline in the sensitivity of some auxin-responsive tissues may occur, or the ability of the nodal sections to take up and/or transport auxin may diminish with time and the build-up of callus at the cut stump.Perhaps a substance accumulates that counteracts inhibition by auxin.For instance, cells at the base of the nodal sections that have begun to differentiate into root tissue may begin to synthesize and release cytokinins.We have established that there is no signi®cant decrease in the potency of the NAA in the split plates during the course of the experiment.Plates used in the assay for 8 days were replenished with fresh nodal sections and were found to inhibit bud outgrowth for as long as fresh plates (data not shown). The assay has also revealed a trend for decreasing sensitivity to inhibition by apical auxin as lateral bud size increases.We have found that some of the larger buds (2± 5 mm), which appear unresponsive to 1 mM NAA, can be inhibited by higher concentrations of apical NAA, but that even 10 mM NAA may not inhibit buds longer than 5 mm (data not shown).Therefore, it appears that, with increasing size, buds loose competence to respond to auxin.The molecular basis for this change is unknown.One possibility is that the transition to auxin resistance corresponds to the establishment of auxin synthesis and transport in the developing bud as suggested by Snow (1937).Certainly, auxin levels increase as buds begin to grow (Gocal et al., 1991;Hillman, 1984;Pearce et al., 1995), and bud activity correlates with the presence of active polar auxin transport (Morris and Johnson, 1990;Morris, 1977). Supplying apical NPA prevented inhibition by apical NAA.This supports the conclusion reached by Tamas et al. (1989) that basipetal auxin transport from the apex is required for bud growth inhibition.In addition, our observation that basally supplied auxins failed to inhibit lateral bud outgrowth is in agreement with their ®ndings.However, they also found that supplying basal IAA to bean nodal explants could relieve inhibition by apical IAA, which is contrary to our results using NAA.This may re¯ect a difference in the action of these speci®c auxins (e.g.uptake into cells), or in the responses of the two species to basal auxin.The difference in the effects of basally and apically supplied auxin is not explained by a difference in the quantity of hormone reaching the bud.By the addition of dyes, we have established that there is signi®cant bulk ¯ow of solutes from the basal media block to the cauline leaf and later to the growing bud in the transpiration stream (data not shown).However, dye supplied in the apical media block did not appear in the leaf or bud.In addition, Lim and Tamas (1989) used 14 C-IAA to show that the quantity of IAA transported to the bud from the cut apical surface of explants did not exceed that reaching the bud from the basal end.We were able to con®rm this result for Arabidopsis explants using 14 C-IAA in our own assay (data not shown).
What the sources say
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Kinetin has also been found to enhance the movement of 32 P and 14 C-sucrose towards the cut stump to which IAA has been applied (Seth and Wareing, 1964).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of cytokinin
What the sources say
- Not checked — no full text of the sourcecites Seth and Wareing, 1964 source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“In plants, the roots are believed to be the major site of cytokinin synthesis (Chen et al., 1985), and to export these substances to the shoot via the xylem.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of cytokinin
What the sources say
- Not checked — no full text of the sourcecites Chen et al., 1985 source
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“Further evidence for a role for ABA in regulating bud growth comes from analysis of the era1 mutant of Arabidopsis which has an enhanced response to ABA and reduced branching (Pei et al., 1998).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of abscisic acid
What the sources say
- Not checked — no full text of the sourcecites Pei et al., 1998 source
plaindirectSingle case- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Individuals were excluded from the data set if the growing bud had touched the medium, if the cut end of the internode had been pushed out of the medium by elongation of the stem, if condensation may have bridged the gap between the two media blocks, or where microbial contamination was visible on the plate.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Set-up and measurements
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“All of the data displayed in this paper represent the growth responses of lateral buds from node 1.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Excising the nodes
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“This trough was checked carefully for any bridges between the two media blocks and dried in the laminar ¯ow hood, parallel to the air¯ow, for a further 30 min.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Split plate production
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
In the paper
“Cytokinins have been shown to stimulate bud outgrowth when applied to the lateral buds of plants with an intact apex, or to decapitated plants to which inhibitory concentrations of apical auxin were applied (Mok, 1994).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > The role of cytokinin
What the sources say
- Not matchedcites Mok, 1994
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Not matched
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The plates were then left at 4°C for at least 72 h to allow the hormone to diffuse evenly throughout the media.”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Split plate production
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper relies on this without support.
The etr1 mutant is ethylene-insensitive.
“the ethylene-insensitive mutant etr1”
The paper relies on this without support.
The abi1-1 and abi2-1 mutants are ABA-insensitive.
“the ABA-insensitive mutants abi1-1 and abi2-1”
The paper relies on this without support.
AVG inhibits ethylene biosynthesis.
“the ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG)”
The paper relies on this without support.
The etr1, abi1, and abi2 mutants used are specific and effective in blocking ethylene action and ABA signalling, respectively, in the assayed buds.
“Our own data, from experiments with AVG and the etr1 mutant, demonstrate that ethylene biosynthesis and ethylene action, respectively, are not required for inhibition of bud outgrowth by apical auxin.”
“Buds from the ABA-insensitive mutants abi1 and abi2 have a wild-type response to apical NAA in the assay.”
The paper relies on this without support.
The excised nodal section assay reproduces the hormonal regulation of axillary bud growth in intact Arabidopsis plants.
“The assay that we have developed, combined with the wide range of Arabidopsis mutants available, is proving a valuable method for investigating the roles of different hormones in the inhibition and outgrowth of lateral buds in Arabidopsis.”
“A comparison of the rates of lateral bud outgrowth from the lowest node of intact Arabidopsis plants (Columbia ecotype) and from the same node on excised untreated sections.”
The paper relies on this without support.
The hormone concentrations used in the assay (e.g., 1 mM NAA, 3 mM ABA) are within a physiological range and their effects reflect natural hormonal roles.
“However, it is also possible that one or more of the observed responses to ABA may be non-physiological, due perhaps to the concentration of the mixed isomers used and/or contact with ectopic tissues.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ The hormonal regulation of axillary bud growth in Arabidopsis > The effect of NPA on auxin-mediated inhibition
“When the polar transport inhibitor 1-N-naphthylphthalamic acid (NPA) was supplied apically (1 mM), inhibition by 1 mM apical NAA was partially relieved (Figure 4b).”
§ The hormonal regulation of axillary bud growth in Arabidopsis > Auxin and bud outgrowth
“Supplying apical NPA prevented inhibition by apical NAA.”
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Sorted by citations
Arabidopsis BRANCHED1 Acts as an Integrator of Branching Signals within Axillary Buds
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“These include elongation growth and apical dominance, processes commonly associated with shade avoidance (Chatfield et al., 2000; Sawa et al., 2002).”
BackgroundLin, H., Wang, R., Qian, Q., Yan, M., Meng, X., Fu, Z., Yan, C., Jiang, B., Su, Z., Li, J., et al. (2009) · The Plant Cell · doi:10.1105/tpc.109.065987 · Cited by 670
“outgrowth of tiller buds of the wild type was significantly promoted, which is consistent with the long-established concept that too little auxin transport also leads to an increased shoot branching (Chatfield et al., 2000).”
BackgroundMolecular Basis of Plant Architecture
Wang, Y., & Li, J. (2008) · Annual Review of Plant Biology · doi:10.1146/annurev.arplant.59.032607.092902 · Cited by 655
Hormonal Interactions in the Regulation of Plant Development
Vanstraelen, M., & Benková, E. (2012) · Annual Review of Cell and Developmental Biology · doi:10.1146/annurev-cellbio-101011-155741 · Cited by 650
Metadata
- Authors
- Chatfield, S. P., Stirnberg, P., Forde, B. G., & Leyser, O.
- Affiliations
- University of York (GB)
- Lancaster University (GB)
- Corresponding author
- Leyser, Ottoline
- Venue
- The Plant Journal
- Publisher
- Wiley
- Published
- 2000-10
- Volume
- 24
- Issue
- 2
- Pages
- 159-169
- ISSN
- 0960-7412 (ISSN-L)
- 1365-313X
- OpenAlex
- W2070702008
- Semantic Scholar
- e5cf2b14ba6d4791675335aae6be357567843f9b
- Cited by
- 284
- References
- 54
- Citations by year
- 2026: 6 · 2025: 12 · 2024: 14 · 2023: 9 · 2022: 19 · 2021: 14 · 2020: 12 · 2019: 12 · 2018: 14 · 2017: 8 · 2016: 14 · 2015: 14 · 2014: 8 · 2013: 8 · 2012: 10
- FWCI
- 14.52
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The Plant Journal (publishedVersion)
- PubMed (publishedVersion)
- Lancaster EPrints (Lancaster University) (submittedVersion)
- White Rose Research Online (University of Leeds, The University of Sheffield, University of York) (submittedVersion)
- Funders
- Directorate for Biological Sciences
- Topics
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Plant Molecular Biology Research
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Plant Parasitism and Resistance
- Life Sciences › Agricultural and Biological Sciences › Plant Science › Flowering Plant Growth and Cultivation
- Keywords
- axillary bud outgrowth, cytokinins, ethylene, abscisic acid, second messengers, Arabidopsis thaliana
- MeSH terms
- Abscisic Acid, Cytokinins, Dose-Response Relationship, Drug, Drug Interactions, Ethylenes, Indoleacetic Acids, Plant Growth Regulators, Arabidopsis, Plant Shoots
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-10, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-10 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Cited sources are checked with a language model’s help (gpt-6-sol).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
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