Qiao Mei-Yu, Zhang Ya-Jun, Liu Li-An, Shi Lei, Ma Qing-Hu, Chow Wah Soon, Jiang Chuang-Dao
Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, People's Republic of China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Photosynth Res. 2021 Aug;149(1-2):57-68. doi: 10.1007/s11120-020-00780-5. Epub 2020 Aug 11.
Plants in their natural environment are often exposed to fluctuating light because of self-shading and cloud movements. As changing frequency is a key characteristic of fluctuating light, we speculated that rapid light fluctuation may induce rapid photosynthetic responses, which may protect leaves against photoinhibition. To test this hypothesis, maize seedlings were grown under fluctuating light with various frequencies (1, 10, and 100 cycles of fluctuations/10 h), and changes in growth, chlorophyll content, gas exchange, chlorophyll a fluorescence, and P700 were analyzed carefully. Our data show that though the growth and light-saturated photosynthetic rate were depressed by rapidly fluctuating light, photosynthesis induction was clearly speeded up. Furthermore, more rapid fluctuation of light strikingly reduced the chlorophyll content, while thermal dissipation was triggered and enhanced. The chlorophyll a fluorescence induction kinetics and P700 absorption results showed that the activities of both photosystem II and photosystem I decreased as the frequency of the fluctuating light increased. In all treatments, the light intensities of the fluctuating light were kept constant. Therefore, rapid light fluctuation frequency itself induced the acceleration of photosynthetic induction and the enhancement of photoprotection in maize seedlings, which play important roles in protecting photosynthetic apparatus against fluctuating high light to a certain extent.
在自然环境中，植物常常因自身遮荫和云层移动而受到波动光的影响。由于变化频率是波动光的一个关键特征，我们推测快速的光波动可能会引发快速的光合反应，这可能会保护叶片免受光抑制。为了验证这一假设，我们将玉米幼苗置于具有不同频率（10小时内1、10和100次波动循环）的波动光下生长，并仔细分析了其生长、叶绿素含量、气体交换、叶绿素a荧光和P700的变化。我们的数据表明，尽管快速波动的光会抑制生长和光饱和光合速率，但光合作用的诱导明显加快。此外，更快的光波动显著降低了叶绿素含量，同时触发并增强了热耗散。叶绿素a荧光诱导动力学和P700吸收结果表明，随着波动光频率的增加，光系统II和光系统I的活性均降低。在所有处理中，波动光的光强保持恒定。因此，快速的光波动频率本身诱导了玉米幼苗光合诱导的加速和光保护的增强，这在一定程度上对保护光合机构免受波动高光的影响起着重要作用。
