高温胁迫对植物光合作用的影响研究进展

孙永江, 王琪, 邵琪雯, 辛智鸣, 肖辉杰, 程瑾

Research Advances on the Effect of High Temperature Stress on Plant Photosynthesis

Yongjiang Sun, Qi Wang, Qiwen Shao, Zhiming Xin, Huijie Xiao, Jin Cheng

图2 高温胁迫下植物光合电子传递链的变化 (A) 光合电子和质子的定向转移依赖于类囊体膜中的关键蛋白复合体; 适宜环境温度下, PSII裂解H2O中的电子主要通过线性电子传递(LEF)至光系统I, 在Fd和FNR的作用下, 将NADP+还原成NADPH, 形成固定CO2所需的还原力; (B) 高温胁迫下, LEF被抑制, PQ库被还原的同时, 依赖NDH及质子梯度调节蛋白/质子梯度调节类似蛋白(PGR5/PGRL1)的环式电子传递(CEF)被激活; LEF的下调可以通过降低传递至光系统I处的电子促进P700的氧化, 而CEF的上调可以通过增加跨膜质子梯度来产生更多的ATP, 也可以通过激发非光化学淬灭来保护光合机构; 因此, 高温胁迫下, LEF和CEF协同作用调节PQ库及P700的氧化还原状态及热耗散, 起到光保护作用。P680和P700分别表示PSII和PSI反应中心叶绿素在可见光谱中的波长吸收峰值。绿色箭头表示LEF转移, 红线表示CEF转移。Fd: 铁氧还蛋白; FNR: 黄素蛋白铁氧还蛋白-NADP还原酶; NADP+: 氧化型烟酰胺腺嘌呤二核苷磷酸; NDH: NA(P)H脱氢酶复合体; PQ: 质体醌; PQH2: 质体醌醇

Figure 2 Changes in the photosynthetic electron transfer chain in plants under high temperature stress (A) The directional transfer of electrons and protons depends on the key protein complexes in thylakoid membranes; under suitable temperature conditions, electrons in H2O oxidized by PSII are mainly transferred to PSI through linear electron flow (LEF), and NADP+ is reduced to NADPH under the action of Fd and FNR, forming the reducing force needed to fix CO2; (B) Under high temperature stress condition, LEF is inhibited, PQ-pool is reduced, and NDH and PGR5 (proton gradient regulation 5)/PGRL1 (proton gradient regulation like 1)-dependent cyclic electron flow (CEF) is activated; the down-regulation of LEF can promote the oxidation of P700 by reducing the electrons transferred to PSI, while the activation of CEF can produce more ATP by increasing the transmembrane proton gradient and protect the photosynthetic apparatus by stimulating non-photochemical quenching. Therefore, under high temperature stress, LEF and CEF synergistically regulate the redox state and heat dissipation of PQ-pool and P700, and thus play a role in photoprotection. P680 and P700 refer to the wavelength absorption peak of chlorophyll in the visible spectrum of PSII and PSI reaction centers, respectively. The green arrow indicates LEF flow, and the red line indicates CEF flow. Fd: Ferredoxin; FNR: Ferredoxin-NADP reductase; NADP+: Oxidized nicotinamide adenine dinucleoside phosphate; NDH: NA(P)H dehydrogenase complex; PQ: Plastoquinone; PQH2: Plastoquinol