A physiological role of cyclic electron transport around photosystem I in sustaining photosynthesis under fluctuating light in rice

Abstract

Plants experience a highly variable light environment over the course of the day. To reveal the molecular mechanisms of their photosynthetic response to fluctuating light, we examined the role of two cyclic electron flows around photosystem I (CEF-PSI)—one depending on PROTON GRADIENT REGULATION 5 (PGR5) and one on NADH dehydrogenase-like complex (NDH)—in photosynthetic regulation under fluctuating light in rice (Oryza sativa L.). The impairment of PGR5-dependent CEF-PSI suppressed the photosynthetic response immediately after sudden irradiation, whereas the impairment of NDH-dependent CEF-PSI did not. However, the impairment of either PGR5-dependent or NDH-dependent CEF-PSl reduced the photosynthetic rate under fluctuating light, leading to photoinhibition at PSI and consequently a reduction in plant biomass. The results highlight that (1) PGR5-dependent CEF-PSI is a key regulator of rapid photosynthetic responses to high light intensity under fluctuating light conditions after constant high light; and (2) both PGR5-dependent and NDH-dependent CEF-PSI have physiological roles in sustaining photosynthesis and plant growth in rice under repeated light fluctuations. The highly responsive regulatory system managed by CEF-PSI appears able to optimize photosynthesis and plant growth under naturally fluctuating light conditions.

Response of linear and cyclic electron flux to moderate high temperature and high light stress in tomato

“…In line with recent studies (Ivanov et al, 2015;Yamori et al, 2016), F v /F m and F v '/F m ' measured as the PSII photochemical efficiency and the antenna efficiency, respectively, in tomato plants under HH were both inhibited in an identical manner to those in peas and rice (Figs. 3a and 3b), where F v is the variable fluorescence which yields in the dark state.…”

“…When photosynthetic organisms are exposed to all kinds of environmental stresses like high or low temperature, water or nutrient stress, and light intensity exceeds the leaf's ability to use it, this can lead to an imbalance between the capability for absorbing light energy and consuming this excess light energy through metabolic mechanisms, resulting in the generation of reactive oxygen species (ROS) which are injurious to photosystems (Chen et al, 2012;Yamori et al, 2016). Extensive research has shown that many sites in the photosynthetic membrane are susceptible to high temperature and high light intensity (HH), in particular photosystem II (PSII) (Pospisil, 2012;Deng et al, 2013).…”

Light Signaling-Dependent Regulation of Photoinhibition and Photoprotection in Tomato

“…In agreement with the role of CEF in the activation of 537 ATP production and qE (Munekage et al, 2004;Yamori et al, 2016) COP1-RNAi and RBOH1-RNAi plants were generated as described previously (Liu et al, Table S3). The PCR product was cloned into pFGC1008-HA …”

The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model

“…The high light levels caused by the focusing effect of the epidermis and the fluctuating light conditions together can pose a significant stress for photosystems in different chloroplasts inside a leaf. In line with this, fluctuating light causes photoinhibition in both rice and Arabidopsis (Kono et al , 2014; Yamori et al , 2016). …”