OsPK2 encodes a plastidic pyruvate kinase involved in rice endosperm starch synthesis, compound granule formation and grain filling

文献类型： 外文期刊

第一作者： Cai, Yicong

作者： Cai, Yicong;Li, Sanfeng;Jiao, Guiai;Sheng, Zhonghua;Wu, Yawen;Shao, Gaoneng;Xie, Lihong;Tang, Shaoqing;Wei, Xiangjin;Hu, Peisong;Peng, Cheng;Xu, Junfeng

作者机构：

关键词： grain filling; amyloplast development; pyruvate kinase; starch biosynthesis; rice

期刊名称：PLANT BIOTECHNOLOGY JOURNAL （ 影响因子：9.803； 五年影响因子：9.555 ）

ISSN： 1467-7644

年卷期： 2018 年 16 卷 11 期

页码：

收录情况： SCI

摘要： Starch is the main form of energy storage in higher plants. Although several enzymes and regulators of starch biosynthesis have been defined, the complete molecular machinery remains largely unknown. Screening for irregularities in endosperm formation in rice represents valuable prospect for studying starch synthesis pathway. Here, we identified a novel rice white-core endosperm and defective grain filling mutant, ospk2, which displays significantly lower grain weight, decreased starch content and alteration of starch physicochemical properties when compared to wild-type grains. The normal starch compound granules were drastically reduced and more single granules filled the endosperm cells of ospk2. Meanwhile, the germination rate of ospk2 seeds after 1-year storage was observably reduced compared with wild-type. Map-based cloning of OsPK2 indicated that it encodes a pyruvate kinase (PK, ATP: pyruvate 2-O-phosphotransferase, EC 2.7.1.40), which catalyses an irreversible step of glycolysis. OsPK2 has a constitutive expression in rice and its protein localizes in chloroplasts. Enzyme assay showed that the protein product from expressed OsPK2 and the crude protein extracted from tissues of wild-type exhibits strong PK activity; however, the mutant presented reduced protein activity. OsPK2 (PKp alpha 1) and three other putative rice plastidic isozymes, PKp alpha 2, PKp beta 1 and PKp beta 2, can interact to form heteromer. Moreover, the mutation leads to multiple metabolic disorders. Altogether, these results denote new insights into the role of OsPK2 in plant seed development, especially in starch synthesis, compound granules formation and grain filling, which would be useful for genetic improvement of high yield and rice grain quality.

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