白及和铁皮石斛对波动光强的光合响应机制

	白及和铁皮石斛对波动光强的光合响应机制; Photosynthetic Responses to Fluctuating Light Intensity in Bletilla striata and Dendrobium officinale
	杨颖婕
导师	张石宝
摘要	The light intensity faced by plants under natural conditions may fluctuate frequently in a short time. Understanding the physiological response of plants to fluctuating light will provide an insight into their ecological adaptation and evolution. In this study, Bletilla striata and Dendrobium officinale were selected to compare their photosynthetic responses to fluctuating light intensity. The main results are as follows: 1. After a sudden transfer from high to low light, the low value of gH+ limited the rate of ATP synthesis, making the Calvin cycle to be restrained by the lack of ATP. This depression of LEF further decreased the rate of ATP regeneration and thus restricted the light use efficiency. During further exposure to low light, AN gradually increased to a stable value because of the recovery of gH+. Taken together, we suggested that the photosynthetic reduction upon transfer from high to low light in B. striata was linked to the slow kinetics of gH+. 2. After a sudden increase in light intensity, cyclic electron transport (CET) was highly elevated to help the rapid formation of ΔpH, providing a sufficient photosynthetic control and restraining the electron flow from PSII to PSI during further high-light exposure. In addition, CET contributed to the synthesis of ATP, accelerating the operation of the Calvin cycle. The activation of CEF played a crucial role in photosynthetic regulation under fluctuating light in B. striata and thus optimizing the trade-off between photoprotection and photosynthesis. 3. Upon an abrupt increase in light intensity, D. officinale showed rapid oxidation of PSI while B. striata displayed an over-reduction of PSI. Furthermore, we found that the rapid oxidation of PSI in D. officinale was mainly attributed to the operation of water-water cycle (WWC) rather than CET. In turn, CET was highly stimulated in B. striata to offset the lack of WWC, avoiding severe photoinhibition of PSI under fluctuating light. Compared with CET, WWC played a more rapid and efficient role in regulating the redox state of PSI in D. officinale. 4. By analyzing the photosynthetic responses to fluctuating light intensity under moderate heat stress in D. officinale and B. striata, we found that PSI activity maintained stable but PSII activity significantly decreased after fluctuating light treatment at 42°C in both species. Upon a sudden increase in irradiance intensity at 42°C, both species showed highly activation of CET. In D. officinale, the high WWC activity contributed to the rapid oxidation of PSI and thus protected PSI in fluctuating light at 42°C. By comparison, heat-induced PSII photoinhibition down-regulated electron flow from PSII and thus protected PSI under fluctuating light in B. striata. The present thesis found that D. officinale and B. striata employed different strategies to cope with fluctuating light, although they belong to the same family.
	2020-11
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74234
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	杨颖婕. 白及和铁皮石斛对波动光强的光合响应机制, Photosynthetic Responses to Fluctuating Light Intensity in Bletilla striata and Dendrobium officinale[D],2020.

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