College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, China.
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.
New Phytol. 2022 Jan;233(1):360-372. doi: 10.1111/nph.17757. Epub 2021 Oct 23.
Past studies have established mesophyll diffusion conductance to CO (g ) as a variable and significant limitation to plant photosynthesis under steady-state conditions. However, the role of g in influencing photosynthesis (A) during the transient period of light induction is largely unknown. We combined gas exchange measurements with laser-enabled carbon isotope discrimination measurements to assess g during photosynthetic induction, using Arabidopsis as the measurement species. Our measurements revealed three key findings: (1) we found that the rate at which g approached steady state during induction was not necessarily faster than the induction rate of the carboxylation process, contradictory to what has been suggested in previous studies; (2) g displayed a strong and consistent coordination with A under both induction and steady-state settings, hinting that the mechanism driving g -A coupling does not require physiological stability as a prerequisite; and (3) photosynthetic limitation analysis of our data revealed that when integrated over the entire induction period, the relative limitation of A imposed by g can be as high as > 35%. The present study provides the first demonstration of the important role of g in limiting CO assimilation during photosynthetic induction, thereby pointing to a need for more research attention to be devoted to g in future induction studies.
过去的研究已经证实，在稳态条件下，胞间 CO2 扩散导度（g）是植物光合作用的一个可变性和重要限制因素。然而，g 在影响光合作用（A）的瞬态光诱导期间的作用在很大程度上是未知的。我们结合气体交换测量和激光碳同位素分馏测量，使用拟南芥作为测量物种，评估了光合作用诱导过程中的 g。我们的测量结果揭示了三个关键发现：（1）我们发现，g 在诱导过程中达到稳态的速率不一定比羧化过程的诱导速率快，这与之前研究中的建议相反；（2）g 在诱导和稳态条件下均与 A 表现出强烈且一致的协调，暗示驱动 g-A 偶联的机制不需要以生理稳定性为前提；（3）对我们数据的光合作用限制分析表明，当整合整个诱导期时，g 对 A 的相对限制作用可高达>35%。本研究首次证明了 g 在限制光合作用诱导期间 CO2 同化过程中的重要作用，因此需要在未来的诱导研究中更加关注 g。
