Evidence of Coexistence of C-3 and C-4 Photosynthetic Pathways in a Green-Tide-Forming Alga, Ulva prolifera

文献类型： 外文期刊

第一作者： Xu, Jianfang

作者： Xu, Jianfang;Mou, Shanli;Zheng, Zhou;Miao, Jinlai;Fan, Xiao;Zhang, Xiaowen;Xu, Dong;Ye, Naihao;Cao, Shaona

作者机构：

期刊名称：PLOS ONE （ 影响因子：3.24； 五年影响因子：3.788 ）

ISSN： 1932-6203

年卷期： 2012 年 7 卷 5 期

页码：

收录情况： SCI

摘要： Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C-3 photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C-4 photosynthesis, so C-4 photosynthesis might be more wide-spread than previously anticipated. Both C-3 and C-4 photosynthesis genes were found in U. prolifera by transcriptome sequencing. We also discovered the key enzymes of C-4 metabolism based on functional analysis, such as pyruvate orthophosphate dikinase (PPDK), phosphoenolpyruvate carboxylase (PEPC), and phosphoenolpyruvate carboxykinase (PCK). To investigate whether the alga operates a C-4-like pathway, the expression of rbcL and PPDK and their enzyme activities were measured under various forms and intensities of stress (differing levels of salinity, light intensity, and temperature). The expression of rbcL and PPDK and their enzyme activities were higher under adverse circumstances. However, under conditions of desiccation, the expression of rbcL and ribulose-1, 5-biphosphate carboxylase (RuBPCase) activity was lower, whereas that of PPDK was higher. These results suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C-4-type carbon metabolism in U. prolifera, probably contributing to its wide distribution and massive, repeated blooms in the Yellow Sea.

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