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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #327592

Title: Identification of large variation in the photosynthetic induction response among 37 soybean genotypes that is not correlated with steady-state photosynthetic capacity

item SOLEH, M - Kyoto University
item TANAKA, Y - Kyoto University
item Kim, Sang Yeol
item Huber, Steven
item SAKODA, K - Kyoto University
item SHIRAIWA, T - Kyoto University

Submitted to: Photosynthesis Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2016
Publication Date: 3/1/2017
Citation: Soleh, M.A., Tanaka, Y., Kim, S., Huber, S.C., Sakoda, K., Shiraiwa, T. 2017. Identification of large variation in the photosynthetic induction response among 37 soybean genotypes that is not correlated with steady-state photosynthetic capacity. Photosynthesis Research. 131(3):305-315.

Interpretive Summary: The increase in photosynthesis that occurs when leaves are transferred from low to high light is referred to as the photosynthetic induction response and typically takes several minutes to reach the new steady-state rate. Because light intensity can vary dramatically and frequently in the field, it is conceivable that differences in the kinetics of photosynthetic induction could be an important determinant of canopy carbon assimilation and therefore, crop yield. Consequently, we examined thirty-seven diverse soybean lines for photosynthetic induction response and steady-state photosynthetic rate in high light. Interestingly, large differences in induction kinetics were observed among the lines, but there was no correlation with photosynthetic capacity or the leaf content of Rubisco activase protein, suggesting that induction is governed by other factors. The genetic variation identified will be useful in future studies that will determine whether photosynthetic induction kinetics could be a breeding target to improve photosynthetic efficiency and crop performance in the field.

Technical Abstract: Irradiance continuously fluctuates during the day in the field, potentially resulting in photosynthetic induction of leaves as they transition from low to high light. The speed of the induction response affects the cumulative carbon gain of the plants and could impact growth and yield. The photosynthetic induction response from a sudden increase in light intensity and its relationship with the photosynthetic capacity under steady state (Pmax) conditions was evaluated in 37 diverse soybean [Glycine max (L.) Merr.] genotypes. With the transition of light intensity from low to high, the induction response of leaf photosynthesis showed large variation among the soybean genotypes. After 5 min illumination with strong light, genotype NAM 23 had the highest leaf photosynthetic rate of 33.8 µmol CO2 m-2 s-1, while genotype NAM 12 showed the lowest rate at 4.7 µmol CO2 m-2 s-1. As a result, cumulative CO2 fixation (CCF) during the first 5 min of high light exposure ranged from a high value of 5.5 mmol CO2 m-2 for NAM23 to a low value of 0.81 mmol CO2 m-2 for NAM12. The difference in the induction response among genotypes was consistent between the vegetative and reproductive stages. However, there was no significant correlation between CCF and Pmax among genotypes. It is suggested that there are different mechanisms regulating Pmax and the induction response. The observed variation in the induction response was mainly attributed to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activation but in preliminary studies soybean lines differing in the induction response did not differ in the leaf content of Rubisco activase a- and ß-proteins. Future studies will be focused on identifying molecular determinants of the photosynthetic induction response and determining whether this trait could be an important breeding target to achieve improved photosynthetic efficiency and growth of soybeans in the field.