Photosynthesis under stressful environments: An overview

In the paper

“For example, it is generally known that in salttolerant species, Chl content increases, whereas it decreases in salt-sensitive species under saline regimes (Hamada and El-Enany 1994, Khan et al. 2009, Akram and Ashraf 2011).”

• Also stated in: § Stress-induced changes · hedged

  “Although the above-cited studies suggest that Chl accumulation could be used as biochemical marker for salt tolerance in different crops, in some other studies, Chl accumulation under saline stress is not always associated with salt tolerance.”

• Also stated in: § Stress-induced changes · plain

  “Therefore using Chl accumulation as an indicator of salt tolerance depends on the nature of the plant species or cultivar.”

What the sources say

• Disputed

  Split into 2 atoms — 0 confirmed, 0 partially supported, 2 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Checked by a reasoning model — may be wrong.

  cites Hamada and El-Enany 1994 sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Khan et al. 2009
• ?Not checked — no full text of the sourcecites Akram and Ashraf 2011 source

In the paper

“A number of reports showed that stomata usually close during the initial stages of drought stress resulting in increased WUE (net CO 2 assimilation rate/transpiration).Stomata closure is known to have a more inhibitory effect on transpiration of water than that on CO 2 diffusion into the leaf tissues (Chaves et al. 2009, Sikuku et al. 2010).”

What the sources say

• Partly supported

  The Introduction (page unavailable) says stomata close in response to drought-related signals and that, under mild stress, a small decline in stomatal conductance may save water and improve water-use efficiency. It does not say closure usually occurs in the initial stages of drought or explicitly compare its inhibitory effects on transpiration and CO2 diffusion; it also qualifies the efficiency benefit as a possibility. (LLM, conf=0.84)

  cites Chaves et al. 2009 sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites Sikuku et al. 2010

In the paper

“The salt-induced alterations in a leaf Chl content could be due to impaired biosynthesis or accelerated pigment degradation.However, during the process of Chl degradation, Chl b may be converted into Chl a, thus resulting in the increased content of Chl a (Fang et al. 1998, Eckardt 2009).”

What the sources say

• Partly supported

  The Introduction (page unavailable) says chlorophyll b is converted to chlorophyll a during degradation. The discussion of the chlorophyll a/b ratio (page unavailable) suggests this conversion may explain a rising ratio during bean-leaf senescence, not an increase in the absolute content of chlorophyll a. The paper studies senescence under air and low oxygen, not salt-induced changes. (LLM, conf=0.88)

  cites Fang et al. 1998 sourceExperimental — accuracy not yet measured
• Partly supported

  The “IN BRIEF A New Chlorophyll Degradation Pathway” section discusses chlorophyll breakdown during leaf senescence, supporting the general possibility of pigment degradation. It does not address salt-induced changes or impaired biosynthesis, and it does not say that chlorophyll b converts to chlorophyll a or that this increases chlorophyll a content. (LLM, conf=0.84)

  cites Eckardt 2009 sourceExperimental — accuracy not yet measured

In the paper

“Heat stress causes membrane disruption, particularly of thylakoid membranes, thereby inhibiting the activities of membrane-associated electron carriers and enzymes (Ristic et al. 2008, Rexroth et al. 2011), which ultimately results in a reduced rate of photosynthesis.”

What the sources say

• ?Not checked — no full text of the sourcecites Ristic et al. 2008 source
• Partly supported

  The Discussion (page not available) links thylakoid membrane fluidity and zeaxanthin content to heat tolerance, supporting a connection between heat and membrane stability. It does not say that heat stress disrupts membranes, inhibits electron carriers or enzymes, or thereby reduces photosynthesis. (LLM, conf=0.77)

  cites Rexroth et al. 2011 sourceExperimental — accuracy not yet measured

In the paper

“A number of reports indicate that plants exposed to high-temperature stress show reduced Chl biosynthesis (Efeoglu and Terzioglu 2009, Balouchi 2010, Reda and Mandoura 2011).”

• Also stated in: § Stress-induced changes · plain

  “The impaired Chl biosynthesis is the first of the processes occurring in plastids affected by the high temperature (Dutta et al. 2009, Li et al. 2010).”

• Also stated in: § Stress-induced changes · plain

  “The inhibition of Chl biosynthesis under high-temperature regimes results from a destruction of numerous enzymes involved in the mechanism of Chl biosynthesis (Dutta et al. 2009, Reda andMandoura 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Efeoglu and Terzioglu 2009 source
• ?Could not verify

  The Introduction (page unavailable) discusses heat-related changes in chlorophyll fluorescence and photosystem II efficiency, not reduced chlorophyll biosynthesis. Searches for biosynthesis, ALAD, ALA, Pchlide, and the proposed enzyme mechanism found no passage addressing those claims in our copy. (LLM, conf=0.72)

  cites Balouchi 2010 sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Reda and Mandoura 2011

In the paper

“The F v /F m ratio is an important parameter, which determines the maximum quantum efficiency of PSII.It provides a measure of the rate of linear electron transport, hence, an indication of overall photosynthetic capacity (Jamil et al. 2007, Tang et al. 2007, Balouchi 2010).”

• Also stated in: § Stress-induced changes · plain

  “In healthy leaves, F v /F m value is usually close to 0.8 in most plant species, therefore a lower value indicates that a proportion of PSII reaction centers is damaged or inactivated, a phenomenon, termed as photoinhibition, commonly observed in plants under stress (Baker and Rosenqvist 2004, Zlatev 2009, Vaz and Sharma 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Jamil et al. 2007 source
• ?Not checked — no full text of the sourcecites Tang et al. 2007 source
• Partly supported

  The Introduction (page not provided) says Fv/Fm indicates maximum PSII efficiency, gives 0.83 for healthy plants, and reports declines under water and heat stress. It does not say that Fv/Fm measures the rate of linear electron transport or overall photosynthetic capacity, or explicitly identify lower values as photoinhibition. (LLM, conf=0.86)

  cites Balouchi 2010 sourceExperimental — accuracy not yet measured

In the paper

“It has been also reported that plants exposed to heat stress for even a short time experience the inhibition of the OEC and the reaction center of PSII (Wang et al. 2010, Hamdani et al. 2011), although the former is more sensitive to heat than the latter.”

• Also stated in: § Stress-induced changes · plain

  “Smith and Low (1989) reported that the PSII core complex undergoes denaturation at about 60 °C, whereas the denaturation of LHCII proteins occurs at about 74°C (Smith et al. 1989).”

• Also stated in: § Stress-induced changes · hedged

  “The major reason considered for heat-induced inactivation of OEC was the release of 33 kDa extrinsic protein from the complex (Zhang et al. 2011).”

What the sources say

• Partly supported

  Split into 3 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

  cites Wang et al. 2010 sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites Hamdani et al. 2011 source
• ?Not checked — no full text of the sourcecites Smith and Low (1989) source

In the paper

“It is known that salinity stress, similarly to other abiotic stresses, can significantly affect both stomatal and nonstomatal regulation of photosynthesis (Ashraf 2004, Saibo et al. 2009).”

• Also stated in: § Stress-induced changes · plain

  “Salt stress imposed at the reproductive stage was reported to decrease the net CO 2 assimilation rate and stomatal conductance of intact leaves in various wheat genotypes (Shahbaz andAshraf 2007, Perveen et al. 2010).”

• Also stated in: § Stress-induced changes · plain

  “The inhibitory effect of salt-induced osmotic stress (water deficit) on the rate of photosynthesis was related to decreased production of ATP due to the impaired electron transport (Moud andMaghsoudi 2008, Curtiss et al. 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Ashraf 2004 source
• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Saibo et al. 2009 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Shahbaz andAshraf 2007

In the paper

“The increase in the amount of Rubisco can be beneficial for the survival of plants under harsh environmental conditions, because a positive relationship of leaf Rubisco contents with P N has been reported in most C 3 plants (Taub 2010, Makino 2011).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Taub 2010
• Partly supported

  In “Difference in Rubisco Properties between Rice and Wheat” (page not provided), the paper says Rubisco amount strongly affects photosynthetic rate and suggests greater allocation to Rubisco may help explain higher rates in rice and wheat. It does not establish a positive relationship between leaf Rubisco content and photosynthesis in most C3 plants, or show that increasing Rubisco improves survival under harsh conditions. (LLM, conf=0.85)

  cites Makino 2011 sourceExperimental — accuracy not yet measured

In the paper

“Similarly as the salt stress, drought stress can also adversely affect levels and activities of different enzymes involved in the mechanism of photosynthesis, thereby impairing the synthesis of carbohydrates as well as WUE of plants, which in turn adversely affects the overall plant yield (Kumar andSingh 2009, Gill et al. 2011).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Kumar andSingh 2009
• Partly supported

  The Results and Discussion report that cadmium stress reduced photosynthetic characteristics in mustard, and the paper concludes that cadmium stress inhibited photosynthesis and yield. Those findings concern cadmium, not drought; our copy does not establish the claimed effects on carbohydrate synthesis or water-use efficiency (WUE). (LLM, conf=0.84)

  cites Gill et al. 2011 sourceExperimental — accuracy not yet measured

In the paper

“Such a strong relationship led to the proposal that the down-regulation of photosynthesis depends more on the availability of CO 2 in the chloroplast than on leaf water content or water potential (Flexas et al. 2002, Saibo et al. 2009, Galmes et al. 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Flexas et al. 2002 source
• Partly supported

  In “Photosynthesis and related mechanisms affected by abiotic stress” (page not provided), the review describes lower chloroplast CO₂ availability as a proposed explanation for reduced photosynthesis under very severe drought, but says evidence for reduced RuBP supply instead conflicts with that view. A reference title contrasts chloroplast CO₂ concentration with relative water content for Rubisco activity; the review does not establish the claimed comparison with leaf water potential or present the proposal as a general rule. (LLM, conf=0.82)

  cites Saibo et al. 2009 sourceExperimental — accuracy not yet measured
• Partly supported

  The Results and discussion (‘Causes for reduced Rubisco activity under water stress’; no page available) report that Rubisco activity correlated more strongly with chloroplastic CO2 concentration than with relative water content. The Concluding remarks likewise propose CO2 availability rather than leaf dehydration as the mediator of reduced Rubisco activity. These passages support the comparison for Rubisco activity, but do not establish it for the down-regulation of photosynthesis as a whole or make a direct comparison with leaf water potential. (LLM, conf=0.84)

  cites Galmes et al. 2011 sourceExperimental — accuracy not yet measured

In the paper

“One of the most prominent effects of various stresses is the stomata closure, which leads to a lower concentration of intercellular CO 2 , which in turn causes deactivation of Rubisco as well as other enzymes such as sucrosephosphate synthase (SPS) and nitrate reductase (Chaves et al. 2009, Mumm et al. 2011).”

What the sources say

• Supported

  The Introduction states that stomatal closure lowers CO2 in leaf airspaces, that low intercellular CO2 can deactivate Rubisco, and that SPS and nitrate reductase activity can decrease after stomatal closure. It also notes that biochemical down-regulation may occur under prolonged stress. (LLM, conf=0.93)

  cites Chaves et al. 2009 source
• ?Not checked — no full text of the sourcecites Mumm et al. 2011 source

In the paper

“For example, a transcription factor LONG HYPOCOTYL 5 (HY5), a bZIP-type, was reported to be mainly involved in the regulation of CAB gene expression by light, although it may also exhibit a significant role in abiotic stress tolerance (Maxwell et al. 2003, Saibo et al. 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Maxwell et al. 2003 source
• Partly supported

  In “Transcription factors mediating the non-stomatal responses to abiotic stress,” the paper identifies HY5 as a bZIP transcription factor involved in light regulation of CAB expression. It says HY5 may play a role in the abiotic stress response, but does not establish a significant role in stress tolerance; it also notes a lack of direct evidence for HY5 regulation of photosynthesis-related genes under abiotic stress. (LLM, conf=0.84)

  cites Saibo et al. 2009 sourceExperimental — accuracy not yet measured

In the paper

“However, in all these transgenic lines, although the activity of C 4 -PEPC increased two-fold compared with that in nontransformed plants, the transgenic and nontransformed lines did not differ significantly in the net CO 2 assimilation rate.”

What the sources say

• Partly supported

  In “Biochemical and Physiological Analyses of Transgenic Tobacco” (page unavailable), the paper reports about twofold higher PPC activity in the four tested transgenic plants. It says photosynthesis rates for lines BVI-6400 (1)–(3) were within experimental error of the control, but line (4) had a significantly lower rate. Thus the claim that none of the lines differed significantly is not supported. (LLM, conf=0.91)

  cites Hudspeth et al. 1992 sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Benfey andChua 1990
• ?Not checked — no full text of the sourcecites Kogami et al. 1994 source

In the paper

“MAPKs respond to a variety of extracellular stimuli including mitogens, proinflammatory cytokines, osmotic stress, and heat shock (Fig. 4), and they pass on information from sensors to cellular processes in all eukaryotes (Nakagami et al. 2005, Diédhiou et al. 2008, Inagaki et al. 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Nakagami et al. 2005 source
• Partly supported

  The Background (page not provided) says MAPKs are involved in osmotic-stress signaling in tobacco and Arabidopsis, and that protein kinases participate in signal transduction in eukaryotes. It does not establish that MAPKs respond to heat shock, mitogens, or proinflammatory cytokines, or that MAPKs convey information from sensors to cellular processes in all eukaryotes. (LLM, conf=0.86)

  cites Diédhiou et al. 2008 sourceExperimental — accuracy not yet measured
• Partly supported

  The Results and Discussion (page not provided) show that osmotic stress activates the MAPK JNK in mouse embryonic fibroblasts. The opening section also links cytokine signaling to MAPKs. Our copy does not establish MAPK responses to heat shock or mitogens, or the claim that MAPKs relay information from sensors to cellular processes in all eukaryotes. (LLM, conf=0.86)

  cites Inagaki et al. 2008 sourceExperimental — accuracy not yet measured

In the paper

“However, transgenic C 3 plants overexpressing multiple C 4 enzymes are now in the focus of most scientists to improve photosynthetic capacity in C 3 plants (Miyao 2003, Begonia and Begonia 2007, Kajala et al. 2012).”

What the sources say

• ?Not checked — no full text of the sourcecites Miyao 2003 source
• Partly supported

  The Leaf function section describes transgenic rice with enhanced activity of the C4 enzyme PEPC and enhanced leaf photosynthesis, calling this work “at the cutting edge of photosynthesis research.” It does not establish that the plants overexpressed multiple C4 enzymes or that they were the focus of most scientists. Page numbers are unavailable in our copy. (LLM, conf=0.86)

  cites Begonia and Begonia 2007 sourceExperimental — accuracy not yet measured
• Partly supported

  The Abstract (page unavailable) says C4 photosynthesis permits higher photosynthetic rates than the ancestral C3 pathway, supporting the rationale for seeking an improvement. It does not say that transgenic C3 plants overexpressing multiple C4 enzymes are a focus of most scientists; the paper instead examines regulation of C4-related genes. (LLM, conf=0.78)

  cites Kajala et al. 2012 sourceExperimental — accuracy not yet measured

In the paper

“In most of the studies on generations of transgenic lines made for enhanced photosynthetic performance that were published so far, a single C 4 enzyme gene has been transferred, but in most cases this did not result in a major success in terms of enhanced photosynthetic capacity in transgenic C 3 lines.”

In the paper

“There is little information on the components involved in either the perception or signaling involved in stress responses.”

In the paper

“Undoubtedly, by integrating the advances in molecular genetics and cell biology, our knowledge of the signaling pathways has increased greatly over recent years, although it is still far from a full understanding to perception and signaling of environmental cues in plants.”

In the paper

“Efforts get currently underway in different laboratories all over the world to identify signaling components, such as transcription factors and protein kinases, particularly MAPKs, involved in stress adaptation in plants.”

In the paper

“However, this organelle is highly sensitive to different stressful environments such as salinity, drought, extremes of temperature, flooding, varying light intensity, and UV radiation, and it plays a premier role in the modulation of stress responses (Biswal et al. 2008, Saravanavel et al. 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Biswal et al. 2008 source
• ?Not checked — no full text of the sourcecites Saravanavel et al. 2011

In the paper

“High concentrations of injurious ions, such as Na + and Cl -, which accumulate in the chloroplasts under salinity stress, are known to damage thylakoid membranes (Wu andZou 2009, Omoto et al. 2010).Electron transport and photophosphorylation of isolated thylakoid membranes were reported to be swiftly and irrevocably inactivated by high concentrations of inorganic salts (Veiga andSilva 2007, Mittal”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Wu andZou 2009
• ?Not checked — no full text of the sourcecites Omoto et al. 2010 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Veiga andSilva 2007

In the paper

“However, in contrast, under severe drought stress, dehydration of mesophyll cells takes place causing a marked inhibition of basic metabolic processes of photosynthesis as well as a reduction of plant WUE (Damayanthi et al. 2010, Anjum et al. 2011).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Damayanthi et al. 2010
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Anjum et al. 2011

In the paper

“Stressful environments such as salinity, drought, and high temperature (heat) cause alterations in a wide range of physiological, biochemical, and molecular processes in plants.Photosynthesis, the most fundamental and intricate physiological process in all green plants, is also severely affected in all its phases by such stresses.”

In the paper

“For example, salt stress can break down chlorophyll (Chl), the effect ascribed to increased level of the toxic cation, Na + (Pinheiro et al. 2008, Li et al. 2010, Yang et al. 2011).Reduction in photosynthetic pigments, such as Chl a and b has been reported in some earlier studies on different crops, e.g., sunflower, Heliantus annuus (Ashraf andSultana 2000, Akram andAshraf 2011), alfalfa, Medicago”

What the sources say

• ?Not checked — no full text of the sourcecites Pinheiro et al. 2008 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Li et al. 2010
• ?Not checked — no full text of the sourcecites Yang et al. 2011 source

In the paper

“The amounts of PSII proteins, such as D1, D2, and LHCII as well as mRNA corresponding to genes of psbA, psbD, and cab, also declined markedly due to water deficit; this was ascribed to decreased rates of transcription and translation as well as fast deterioration of proteins and mRNAs (Duan et al. 2006, Liu et al. 2009).”

• Also stated in: § Stress-induced changes · plain

  “Phosphorylation and dephosphorylation of PSII are the main regulatory factors and they play a major role in PSII repair.”

• Also stated in: § Stress-induced changes · boosted

  “Liu et al. (2009) have shown that water stress caused the rapid dephosphorylation of PSII proteins, coupled with the phosphorylation of LHCII b4 and CP29, in barley (Hordeum vulgare).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Duan et al. 2006
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Liu et al. 2009

In the paper

“Photosynthesis is sensitive to changes in temperature, but a reversible decline has been observed under mild temperature stress, while a permanent impairment was found after an exposure to severe heat stress.”

• Also stated in: § Stress-induced changes · plain

  “At high temperatures, PSII and stroma become oxidized and a significant reduction takes place in PSI.”

In the paper

“PSII has been long believed to be a prominent heat sensitive component of photosynthesis (Schrader et al. 2004), but it can perform normal functioning up to 45°C (Gombos et al. 1994).”

• Also stated in: § Stress-induced changes · hedged

  “However, there are some reports showing that moderately high temperature (35-45°C) can induce the cyclic transport of electrons and thylakoid membranes become leaky (Sharkey 2005).”

• Also stated in: § Stress-induced changes · hedged

  “The deactivation of Rubisco at mild heat stress could be attributed to the deleterious effects of heat on chloroplast reactions (Sharkey 2005, Velikova et al. 2012).”

What the sources say

• ?Not checked — no full text of the sourcecites Schrader et al. 2004 source
• ?Not checked — no full text of the sourcecites Gombos et al. 1994 source
• ?Not checked — no full text of the sourcecites Sharkey 2005 source

In the paper

“From a number of studies, it is evident that changes occurring in the ultrastructure of thylakoid membranes above 40°C cause dissociation of the LHCII Chl a/b-proteins from the PSII core complex (Tang et al. 2007, Iwai et al. 2010).”

• Also stated in: § Stress-induced changes · plain

  “However, heat-induced alteration in these proteins leads to destacking of the appressed membranes of the granum (Fristedt et al. 2009, Lemeille andRochaix 2010), which is mediated by the separation of nonbilayer-forming lipids.”

• Also stated in: § Stress-induced changes · hedged

  “As in the case of drought stress, phosphorylation and dephosphorylation of thylakoid proteins has been suggested to play a critical role in responses of plants to elevated temperature (Krishnan andPueppke 1987, Conde et al. 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Tang et al. 2007 source
• ?Not checked — no full text of the sourcecites Iwai et al. 2010 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Fristedt et al. 2009

In the paper

“Carotenoids (Car) are necessary for photoprotection of photosynthesis and they play an important role as a precursor in signaling during the plant development under abiotic/biotic stress.”

• Also stated in: § Stress-induced changes · plain

  “Recently, working with sugar cane, Gomathi and Rakkiyapan (2011) found that imposition of salt stress (7-8 dS m -1 ) at various plant growth stages caused a marked reduction in Chl and Car contents, but salt-tolerant varieties exhibited higher membrane stability and pigment contents.”

• Also stated in: § Stress-induced changes · plain

  “A considerable reduction (about 52%) in Chl/Car ratio was reported in wheat plants under high-temperature stress (Yildiz and Terzi 2008).”

What the sources say

• ?Not checked — no full text of the sourcecites Gomathi and Rakkiyapan (2011) source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Yildiz and Terzi 2008

In the paper

“A number of studies conducted in vivo have shown that drought stress causes considerable damage to the oxygen evolving center (OEC) coupled with PSII (Skotnica et al. 2000, Kawakami et al. 2009) as well as degradation of D1 polypeptide leading to the inactivation of the PSII reaction center (He et al. 1995, Liu et al. 2006, Zlatev 2009).”

• Also stated in: § Stress-induced changes · plain

  “The changes lead to the generation of reactive oxygen species (ROS), which ultimately cause the photoinhibition and oxidative damage (Ashraf 2009, Gill and Tuteja 2010, Anjum et al. 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Skotnica et al. 2000 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites He et al. 1995
• ?Not checked — no full text of the sourcecites Ashraf 2009 source

In the paper

“The salinity-induced osmotic effect on plants causes a substantial accumulation of abscisic acid (ABA), particularly in the guard cells of stomata, which consequently leads to a partial stomata closure thereby lowering the stomatal conductance as well as substomatal CO 2 concentration (Zhao et al. 2009b).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Zhao et al. 2009b

In the paper

“The xanthophyll cycle, particularly the de-epoxidation of violaxanthin to zeaxanthin through antheraxanthin, was reported to play an important role in energy dissipation at high light intensity (Demmig-Adams and Adams 1992, Misra et al. 2006).”

• Also stated in: § Stress-induced changes · plain

  “The dissipation of excitation energy is determined as nonphotochemical quenching (NPQ) of Chl fluorescence during photosynthetic electron transport, which significantly correlates with contents of zeaxanthin and antheraxanthin produced during the xanthophyll cycle (Niyogi et al. 1997).”

What the sources say

• ?Not checked — no full text of the sourcecites Demmig-Adams and Adams 1992 source
• ?Not checked — no full text of the sourcecites Misra et al. 2006 source
• ?Not checked — no full text of the sourcecites Niyogi et al. 1997 source

In the paper

“Although the photochemical efficiency of PSII was similar in both cabbage and kidney bean seedlings, the de-epoxidation state of violaxanthin increased six-fold in kidney bean, while no significant change was observed in cabbage under saline treatments.Similarly, NPQ increased in kidney bean, but decreased in cabbage.”

• Also stated in: § Stress-induced changes · hedged

  “Thus, the increase in the de-epoxidation state of violaxanthin in salt-stressed kidney plants may be a signal to shield the pigment-protein complexes from salt-induced photodamage (Misra et al. 2006).”

What the sources say

• ?Not checked — no full text of the sourcecites Misra et al. 2006 source

In the paper

“Photosynthetic pigments present in the photosystems are believed to be damaged by stress factors resulting in a reduced light-absorbing efficiency of both photosystems (PSI and PSII) and hence a reduced photosynthetic capacity (Geissler et al. 2009, Zhang et al. 2011).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Geissler et al. 2009
• ?Not checked — no full text of the sourcecites Zhang et al. 2011 source

In the paper

“As salinity stress, drought stress causes not only a substantial damage to photosynthetic pigments, but it also leads to deterioration of thylakoid membranes (Huseynova et al. 2009, Anjum et al. 2011, Kannan and Kulandaivelu 2011).”

• Also stated in: § Stress-induced changes · plain

  “The decrease in Chl content is a commonly observed phenomenon under drought stress (Bijanzadeh and Emam 2010, Mafakheri et al. 2010, Din et al. 2011).”

• Also stated in: § Stress-induced changes · boosted

  “It is generally known that under drought stress the reduction of Chl b is greater than that of Chl a, thus, transforming the ratio in favor of Chl a (Jaleel et al. 2009, Jain et al. 2010).”

What the sources say

• ?Not checked — no full text of the sourcecites Huseynova et al. 2009 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Anjum et al. 2011
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Kannan and Kulandaivelu 2011

In the paper

“For example, some studies have shown a significant inhibitory effect of salinity on PSII activity (Everard et al. 1994, Akram and Ashraf 2011, Saleem et al. 2011), whereas other reports found no significant effect on the structure and function of PSII (Al-Taweel et al. 2007, Abdeshahian et al. 2010).”

• Also stated in: § Stress-induced changes · plain

  “Recently, Mehta et al. (2010) have reported that the donor side of the PSII was damaged more than the acceptor side due to salt stress (0.1-0.5 M NaCl) in wheat (Triticum aestivum).”

• Also stated in: § Stress-induced changes · plain

  “Furthermore, the salt-induced damage to PSII was reversible, because 100% recovery of the acceptor side and about 85% of the donor side has been reported (Mehta et al. 2010).”

What the sources say

• ?Not checked — no full text of the sourcecites Everard et al. 1994 source
• ?Not checked — no full text of the sourcecites Al-Taweel et al. 2007 source
• ?Not checked — no full text of the sourcecites Mehta et al. 2010 source

In the paper

“CO 2 -exchange characteristics have been regarded an important indicator of the growth of plants, because of their direct link to net productivity (Ashraf 2004, Piao et al. 2008).”

• Also stated in: § Stress-induced changes · hedged

  “However, the effect of any stress on photosynthesis could be caused by stomatal, nonstomatal or both factors (Athar andAshraf 2005, Saibo et al. 2009), nevertheless, the extent of stress-induced stomatal or nonstomatal regulation depends on the species.”

What the sources say

• ?Not checked — no full text of the sourcecites Ashraf 2004 source
• ?Not checked — no full text of the sourcecites Piao et al. 2008 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Athar andAshraf 2005

In the paper

“Despite the fact that the extent of Chl fluorescence does not comprise more than 1-2% of total light absorbed by the Chl, its measurement is convenient and noninvasive.It gives a valuable insight into exploitation of the excitation energy by PSII, and indirectly by the other protein complexes of the thylakoid membranes (Walker 1987, Roháček 2002), particularly in plants exposed to stressful”

What the sources say

• ?Not checked — no full text of the sourcecites Walker 1987
• ?Not checked — no full text of the sourcecites Roháček 2002 source

In the paper

“It is evident that drought, salinity, and high-temperature stress adversely affect the functionality of both photosystems and reduce electron transport through them.”

• Also stated in: § Stress-induced changes · plain

  “This results in a low production of ATP and NADPH, the two main products of the light reactions (electron transport), which are essential for CO 2 fixation in the dark reactions of the photosynthesis.”

• Also stated in: § Stress-induced changes · plain

  “Thus, stress-induced impairment of the photosystems ultimately limits the CO 2 reduction process.”

In the paper

“However, a relationship of g s with leaf water potential or RWC was not observed, i.e., reduced photosynthesis caused by water-deficit conditions occurred at different leaf water levels in different species, even though at similar g s (Athar andAshraf 2005, Peri et al. 2009).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Athar andAshraf 2005
• ?Not checked — no full text of the sourcecites Peri et al. 2009 source

In the paper

“Abdel-Latif (2008) observed that although the activities of phosphoenolpyruvate carboxylase (PEPC) isolated from wheat (C 3 plant) and that from maize (C 4 plant) were inhibited under saline regimes, the enzyme from wheat was less sensitive to salt than that from maize (Table 2).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Abdel-Latif 2008

In the paper

“Photosynthetic capacity (rate of photosynthesis) has also been considered as one of the potential indicators of heat-stress tolerance in different plant species, because the gas-exchange characteristic showed a positive association with the drought tolerance in different species or cultivars within the species in several studies, e.g., tomato (Camejo et al. 2005, Singh et al. 2005) and melon (Kit”

What the sources say

• ?Not checked — no full text of the sourcecites Camejo et al. 2005 source
• ?Not checked — no full text of the sourcecites Singh et al. 2005 source
• ?Not checked — no full text of the sourcecites Kitroongruang et al. 1992 source

In the paper

“However, such a positive relationship of photosynthetic capacity to drought tolerance is not a general rule and in other studies the reverse results were obtained.”

In the paper

“Similarly, in another study with potato, a transgenic line expressing the chloroplastic fructose-1,6-bisphosphatase at less than 15% compared with the wild-type plants showed considerably reduced P N and growth; it shows that the enzyme has a key role in the regulation of the Calvin cycle (Kossman et al. 1994).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Kossman et al. 1994

In the paper

“Thus, it is likely that either water deficit has no effect on photosynthesis until a threshold is reached, beyond which it is impaired or a consistent suppression in metabolism is caused (Lawlor 2002, Athar and Ashraf 2005, Lawlor and Tezara 2009).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Lawlor 2002
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Athar and Ashraf 2005
• ?Not checked — no full text of the sourcecites Lawlor and Tezara 2009 source

In the paper

“It has also been shown that leaves that survive drought often show higher rates of photosynthesis (Ludlow and Ng 1974, Akram et al. 2007, Bayramov et al. 2010) and of Rubisco content per unit leaf area (David et al. 1998, Kumar andSingh 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Ludlow and Ng 1974 source
• ?Not checked — no full text of the sourcecites Akram et al. 2007
• ?Not checked — no full text of the sourcecites Bayramov et al. 2010 source

In the paper

“In another study with two species of rice, Ghosh et al. (2001) found that not only Rubisco is affected, but also the enzymes involved in regeneration of the Rubisco substrate, ribulose-1,5-bisphophate (RuBP) are regulated by salt stress and they can play a key role in the regulation of the Calvin cycle (Table 2).”

What the sources say

• ?Not checked — no full text of the sourcecites Ghosh et al. 2001 source

In the paper

“For example, in subterranean clover (Trifolium subterraneum), water deficit conditions reduced the initial and total Rubisco activity, but it did not decrease the overall amount of Rubisco protein per unit of leaf area (Medrano et al. 1997).”

What the sources say

• ?Not checked — no full text of the sourcecites Medrano et al. 1997 source

In the paper

“Chinthapalli et al. (2003) showed that the PEPCase from the C 4 plant (Amaranthus hypochondriacus) was less sensitive to supraoptimal temperature, but more sensitive to suboptimal temperature than the enzyme from the C 3 species (Pisum sativum).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Chinthapalli et al. 2003

In the paper

“They showed that the overexpression of glutamine synthetase significantly reduced the tissue Na + content under saline regimes, suggesting the putative role of this enzyme in salt tolerance of rice.”

What the sources say

• ?Not checked — no full text of the sourcecites Tanaka et al. 2005 source

In the paper

“This transgenic line showed a 30% increase in WUE and a 20% increase in dry biomass under moderate waterdeficit conditions.”

What the sources say

• ?Not checked — no full text of the sourcecites Jeanneau et al. 2002 source

In the paper

“Two approaches are currently used to improve the photosynthetic capacity in different plant species.Firstly, an effort is devoted to developing transgenic C 3 plants with over-expression of Rubisco genes or other enzymes of the C 3 pathway.Secondly, attempts are underway to transfer the genes of a key C 4 photosynthetic pathway to C 3 plants (Table 3).”

In the paper

“Furthermore, a number of enzymes of both CO 2 concentrating mechanisms are regulated by light (Taiz andZeiger 2010, Doubnerová andRyšlavá 2011), so the light intensity and its duration in addition to the intensity of additional stress play also a significant role in the regulation of these enzymes.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Taiz andZeiger 2010
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Doubnerová andRyšlavá 2011

In the paper

“For example, in wheat (Triticum aestivum), heat stress imposed for 12 days caused a sharp decline in Rubisco activity, whereas the activity of PEPC increased first, but later decreased, which caused a marked increase in PEPC/Rubisco ratio (Xu et al. 2003).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Xu et al. 2003

In the paper

“They suggested that the enhanced rate of photosynthesis under salt stress might have been due to the enhanced supply of RuBP to Rubisco by the activation of SBPase.”

What the sources say

• ?Not checked — no full text of the sourcecites Feng et al. 2007 source

In the paper

“In another study concerning nonstomatal limitations of photosynthesis, Du et al. (1998) reported that the activities of the various C 4 photosynthesis enzymes, such as PEPcase, NADPmalic enzyme (NADP-ME), Rubisco, and fructose-1,6bisphosphatase, decreased 2 to 4 times under drought conditions, whereas the activity of phosphopyruvate dikinase (PPDK) declined 9.1 times in C 4 plant, sugar cane.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Du et al. 1998

In the paper

“It has also been observed that under most stresses the balance between different enzymes is also perturbed.”

In the paper

“They showed that a 68% decrease in Rubisco activity did not hamper P N under water-limited regimes, suggesting that drought stress may affect any of the steps involved in the regeneration of RuBP rather than Rubisco itself.”

What the sources say

• ?Not checked — no full text of the sourcecites Gunasekera and Berkowitz 1993 source

In the paper

“In another study, Marques and Arrabica (1995) found that Rubisco activity in Setaria sphacelota declined slightly under moderate drought, but substantially under severe drought.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Marques and Arrabica 1995

In the paper

“Using the first strategy, Feng et al. (2007) produced a transgenic line of japonica rice by overexpressing OsSbp cDNA from an indica rice cultivar.This transgenic line showed beside an enhanced activity of the C 3 enzyme sedoheptulose-l,7-bisphosphatase (SBPase, EC 3.1.3.37), which is involved in the regeneration of RuBP, also the enhanced photosynthetic capacity as well as the increased tolerance”

What the sources say

• ?Not checked — no full text of the sourcecites Feng et al. 2007 source

In the paper

“It depends undoubtedly on a multitude of factors including the partitioning of introduced C 4 enzymes within the leaf tissues and the interlinking of C 4 enzymes with photosynthesis-related pathways functioning in C 3 plants.”

In the paper

“It has been observed that although overexpression of a single C 4 enzyme can modulate the photosynthetic metabolism in C 3 plants, in most cases, it does not have significant effects on photosynthesis.”

In the paper

“Photosynthetic response to different types of stresses is quite intricate, because it entails the interaction of several restrictions occurring at different locations of the cell or the leaf, and at different phases of the plant growth and development.”

In the paper

“The enhanced drought tolerance of the transgenic line of maize was shown to be strongly associated with a markedly high rate of photosynthesis, suggesting the active role of NPK1 in the mechanism of protection of photosynthesis machinery from water stress damage.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Shou et al. 2004

In the paper

“They are known to regulate a multitude of cellular processes, such as mitosis, differentiation, gene expression, and cell death or survival (Zhang and Klessig 2001).”

What the sources say

• ?Not checked — no full text of the sourcecites Zhang and Klessig 2001 source

In the paper

“It is not clear yet up to what extent C 4 enzymes transferred to C 3 plants take part in effective assimilation of CO 2 in C 3 engineered plants.”

In the paper

“However, it is not easy to discriminate between the effects of these limitations on overall photosynthetic capacity of a plant.”