The decline in photosynthetic rate upon transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase in Bletilla striata

Upon a sudden transition from high to low light, the rate of CO 2 assimilation ( A N ) in some plants first decreases to a low level before gradually becoming stable. However, the underlying mechanisms remain controversial. The activity of chloroplast ATP synthase ( g H + ) is usually depressed unde...

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Bibliographic Details
Published in:Photosynthesis research 2020-04, Vol.144 (1), p.13-21
Main Authors: Yang, Ying-Jie, Zhang, Shi-Bao, Wang, Ji-Hua, Huang, Wei
Format: Article
Language:English
Subjects:
ATP synthase
Biochemistry
Biomedical and Life Sciences
Bletilla striata
Carbon dioxide
Chlorophyll
Chloroplast Proton-Translocating ATPases - metabolism
Chloroplasts
Gas exchange
Kinetics
Life Sciences
Light
Orchidaceae - enzymology
Original Article
Photosynthesis
Photosynthesis - physiology
Plant Genetics and Genomics
Plant Physiology
Plant Sciences
Redox properties
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Summary:Upon a sudden transition from high to low light, the rate of CO 2 assimilation ( A N ) in some plants first decreases to a low level before gradually becoming stable. However, the underlying mechanisms remain controversial. The activity of chloroplast ATP synthase ( g H + ) is usually depressed under high light when compared with low light. Therefore, we hypothesize that upon a sudden transfer from high to low light, the relatively low g H + restricts ATP synthesis and thus causes a reduction in A N . To test this hypothesis, we measured gas exchange, chlorophyll fluorescence, P700 redox state, and electrochromic shift signals in Bletilla striata (Orchidaceae). After the transition from saturating to lower irradiance, A N and ETRII decreased first to a low level and then gradually increased to a stable value. Within the first seconds after transfer from high to low light, g H + was maintained at low levels. During further exposure to low light, g H + gradually increased to a stable value. Interestingly, a tight positive relationship was found between g H + and ETRII. These results suggested that upon a sudden transition from high to low light, A N was restricted by g H + at the step of ATP synthesis. Taken together, we propose that the decline in A N upon sudden transfer from high to low light is linked to the slow kinetics of chloroplast ATP synthase.
ISSN:0166-8595
1573-5079
DOI:10.1007/s11120-020-00725-y