Light sheet microscopy reveals more gradual light attenuation in light-green versus dark-green soybean leaves.

In soybean, greater rates of Aleaf on an absorbed photon basis were evident in light-green soybean leaves, and the increase in Aleaf correlated with a more even light distribution among chloroplasts within leaves.

“In soybean, greater rates of Aleaf on an absorbed photon basis were evident in light-green soybean leaves, and the increase in Aleaf correlated with a more even light distribution among chloroplasts within leaves (Slattery et al., 2016).”

Light sheet microscopy analyses revealed more gradual PPFD attenuation in light-green soybean leaves compared to dark-green leaves, resulting in significantly more red and blue light reaching the spongy mesophyll chloroplasts of the light-green leaves, which correlated with greater photosynthetic light use efficiency.

“Light sheet microscopy analyses revealed more gradual PPFD attenuation in light-green soybean leaves compared to dark-green leaves. This resulted in significantly more red and blue light reaching the spongy mesophyll chloroplasts of the light-green leaves, which correlated with greater photosynthetic light use efficiency (Slattery et al., 2016).”

Similar responses to severe reductions in chl content (>80%) seen in y9y9 have been reported in Y11y11 when grown in controlled environment chambers at lower than field light levels.

“Similar responses to severe reductions in chl content (>80%) seen in y9y9 have been reported in Y11y11 when grown in controlled environment chambers at lower than field light levels (Xu et al., 1993; Slattery et al., 2016).”

The 22% reduction in leafabs is less than the reduction predicted by Beer's law.

“Benefits to Aleaf were seen only when chl content in Y11y11 was reduced to 30–40% of WT (Figures 2C,D), which corresponded to a 22% reduction in leafabs (Figure 3) that is less than the reduction predicted by Beer’s law (Slattery et al., 2016).”

In dark-green leaves, the majority of light absorption occurs in the uppermost adaxial chloroplasts, causing light limitation in lower chloroplasts.

“In dark-green leaves, the majority of light absorption occurs in the uppermost adaxial chloroplasts, causing light limitation in lower chloroplasts (Vogelmann and Evans, 2002; Evans and Vogelmann, 2003; Slattery et al., 2016).”

Leaf thickness did not change in a previous study on the same soybean genotypes, even when SLW was significantly different.

“Although leaf thickness was not directly measured in this study, leaf thickness did not change in a previous study on the same soybean genotypes, even when SLW was significantly different (Slattery et al., 2016).”