NADPH from the oxidative pentose phosphate pathway drives the operation of cyclic electron flow around photosystem I in high-intertidal macroalgae under severe salt stress
NADPH from the oxidative pentose phosphate pathway drives the operation of cyclic electron flow around photosystem I in high-intertidal macroalgae under severe salt stress
复制标题
严重盐胁迫下，氧化戊糖磷酸途径中的 NADPH 驱动高潮间带大型藻类光系统 I 周围循环电子流的运行
DOI：
10.1111/ppl.12383
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发表时间：
2016-04-01
影响因子：
6.4
通讯作者：
Wang, Guangce
中科院分区：
文献类型：
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作者：
Lu, Xiaoping;Huan, Li;Wang, Guangce
yezoensis （Bangiales, Rhodophyta）是高潮间带大型藻类的代表物种，其叶片可以耐受极端胁迫，如盐胁迫和干燥。研究了盐胁迫下紫杉树叶片的光系统响应。结果表明，在高盐胁迫下，当PS (Y) II的有效光化学量子产率几乎为零时，YI仍具有较高的活性率。因此PSII比PSI对盐胁迫更敏感。此外，在3-（3,4 -二氯苯基）-1,1-二甲基脲（DCMU）存在下，YI随盐度升高而升高。葡萄糖-6-磷酸脱氢酶（EC 1.1.1.49, G6PDH）抑制剂（glucosamine, Glucm）存在时，dcmu处理的菌体YI值降低。在甲基紫紫素（MV）存在时，YI值接近0.09，在二溴百里醌（DBMIB）存在时，YI值几乎为零。这些结果表明，在严重的盐胁迫（盐度为1200ppm）下，PSI活性不是由PSII驱动的，基质还原剂可能支持PSI的运行。在盐胁迫下，淀粉含量降低，可溶性糖含量升高。G6PDH和6-磷酸葡萄糖酸脱氢酶（EC 1.1.1.44）活性升高，而胞质甘油醛3-磷酸脱氢酶（EC 1.2.1.12）活性降低。NADPH含量升高，但NADH含量降低，表明可溶性糖进入了氧化戊糖磷酸途径（OPPP）。这些结果表明，OPPP的NADPH增加了高潮间带大型藻类在严重盐胁迫下PSI周围的循环电子流。
Pyropia yezoensis (Bangiales, Rhodophyta) is a representative species of high-intertidal macroalgae, whose blades can tolerate extreme stresses, such as salt stress and desiccation. In this study, the photosystem (PS) responses of P. yezoensis blades under salt stress were studied. Our results showed that when the effective photochemical quantum yield of PS (Y) II decreased to almost zero under high salt stress, YI still had a relatively high activity rate. PSII was therefore more sensitive to salt stress than PSI. Furthermore, in the presence of 3-(3, 4-dichlorophenyl)-1,1-dimethylurea (DCMU), YI rose as salinity increased. The YI values for DCMU-treated thalli decreased in the presence of glucose-6-phosphate dehydrogenase (EC 1.1.1.49, G6PDH) inhibitor (glucosamine, Glucm). The YI values were approximate to 0.09 in the presence of methyl viologen (MV) and almost zero in the presence of dibromothymoquinone (DBMIB). These results demonstrated that under severe salt stress (120 parts per thousand salinity) PSI activity was driven from a source other than PSII, and that stromal reductants probably supported the operation of PSI. Under salt stress, the starch content decreased and soluble sugar levels increased. The G6PDH and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) activities increased, but cytosolic glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.12) activity decreased. Furthermore, the NADPH content increased, but NADH decreased, which suggested that soluble sugar entered the oxidative pentose phosphate pathway (OPPP). All these results suggested that NADPH from OPPP increases the cyclic electron flow around PSI in high-intertidal macroalgae under severe salt stress.