Sun Hu, Shi Qi, Liu Ning-Yu, Zhang Shi-Bao, Huang Wei
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
Plant Physiol Biochem. 2023 Mar;196:152-161. doi: 10.1016/j.plaphy.2023.01.044. Epub 2023 Jan 24.
Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly delayed the induction kinetics of stomatal and mesophyll conductances after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly suppressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only caused a larger loss of carbon gain under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO fixation and thus favored PSI photoprotection under FL. To our knowledge, we here show new insight into how drought stress affects photosynthetic performance under FL.
波动光（FL）和干旱胁迫通常同时发生。然而，干旱胁迫是否会影响波动光下的光合性能仍不清楚。在此，我们测定了干旱胁迫下番茄（Solanum lycopersicum）幼苗在波动光下的气体交换、叶绿素荧光和P700氧化还原状态。干旱胁迫显著延迟了从低光过渡到高光后气孔导度和叶肉导度的诱导动力学，从而延迟了波动光下的光合诱导。因此，干旱胁迫加剧了波动光下碳同化的损失。此外，干旱胁迫下对CO固定的限制加剧了从低光过渡到高光时光系统I（PSI）的过度还原。由此产生的更强的波动光诱导的PSI光抑制显著抑制了线性电子流和PSI光保护。这些结果表明，干旱胁迫不仅导致波动光下碳同化的更大损失，还加速了波动光诱导的PSI光抑制。此外，干旱胁迫增强了波动光下的相对循环电子流，这部分补偿了受限制的CO固定，从而有利于波动光下的PSI光保护。据我们所知，我们在此展示了关于干旱胁迫如何影响波动光下光合性能的新见解。
