Cyclic Electron Transport around PSI Contributes to Photosynthetic Induction with Thioredoxin f
Cyclic Electron Transport around PSI Contributes to Photosynthetic Induction with Thioredoxin f
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DOI：
10.1104/pp.20.00741
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发表时间：
2020-11-01
期刊：
影响因子：
7.4
通讯作者：
Motohashi, Ken
中科院分区：
文献类型：
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作者：
Okegawa, Yuki;Basso, Leonardo;Motohashi, Ken
为了响应光，植物有效地诱导光合作用。硫氧还蛋白（Trx）系统对巯基酶的光活化和质子梯度调节5（PGR 5）依赖性途径的循环电子传递对光合作用的调节有重要作用。拟南芥（拟南芥）突变体缺乏f-型Trxs（trx f1 f2）显示延迟激活的碳同化由于受损的光还原卡尔文-本森循环酶。为了进一步研究光合作用诱导过程中的效率，有助于监管机制，我们分析了PSI供体和受体侧调控的trx f1 f2突变体的背景下的贡献。细胞色素B（6）f复合物参与PSI供体侧调节，而PGR 5依赖性PSI循环电子传递是供体和受体功能所必需的。将细胞色素B（6）f复合物活性有条件缺陷的pgr 1突变引入trx f1 f2突变体背景中，不会进一步影响光合作用的诱导，但Trx f和PGR 5的联合缺乏严重损害光合作用并抑制植物在长日照条件下的生长。在pgr 5 trx f1 f2突变体中，PSI的受体侧几乎完全减少，并且PSII和PSI的量子产率在光合诱导过程中几乎没有增加。我们还比较了trx f1 f2和pgr 5 trxf 1f 2突变体之间的巯基酶的光还原。pgr 5突变并没有导致进一步受损的光还原的卡尔文-本森循环酶或ATP合酶的trx f1 f2突变体的背景。这些结果表明，受体侧的限制在pgr 5 trx f1 f2突变体抑制光合作用的启动，这表明PGR 5是需要有效的光合作用诱导。
In response to light, plants efficiently induce photosynthesis. Light activation of thiol enzymes by the thioredoxin (Trx) systems and cyclic electron transport by the PROTON GRADIENT REGULATION5 (PGR5)-dependent pathway contribute substantially to regulation of photosynthesis. Arabidopsis (Arabidopsis thaliana) mutants lacking f-type Trxs (trx f1f2) show delayed activation of carbon assimilation due to impaired photoreduction of Calvin-Benson cycle enzymes. To further study regulatory mechanisms that contribute to efficiency during the induction of photosynthesis, we analyzed the contributions of PSI donor- and acceptor-side regulation in the trx f1f2 mutant background. The cytochrome b(6)f complex is involved in PSI donor-side regulation, whereas PGR5-dependent PSI cyclic electron transport is required for both donor and acceptor functions. Introduction of the pgr1 mutation, which is conditionally defective in cytochrome b(6)f complex activity, into the trx f1f2 mutant background did not further affect the induction of photosynthesis, but the combined deficiency of Trx f and PGR5 severely impaired photosynthesis and suppressed plant growth under long-day conditions. In the pgr5 trx f1f2 mutant, the acceptor-side of PSI was almost completely reduced, and quantum yields of PSII and PSI hardly increased during the induction of photosynthesis. We also compared the photoreduction of thiol enzymes between the trx f1f2 and pgr5 trxf1f2 mutants. The pgr5 mutation did not result in further impaired photoreduction of Calvin-Benson cycle enzymes or ATP synthase in the trx f1f2 mutant background. These results indicated that acceptor-side limitations in the pgr5 trx f1f2 mutant suppress photosynthesis initiation, suggesting that PGR5 is required for efficient photosynthesis induction.