Leaf senescence, which affects plant growth and yield in rice, is an ideal target for crop improvement and remarkable advances have been made to identify the mechanism underlying this process. We have characterized an early senile mutant es5 (early leaf senescence 5) in rice exhibiting leaf yellowing phenotype after the 4-leaf stage. This phenotype was confirmed by the higher accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), the disintegration of chloroplasts, reduction in chlorophyll content and photosynthetic rate and up-regulation of senescence-associated genes (SAGs) like Osh36, OsI57, and OsI85. Positional cloning revealed that the es5 phenotype is the result of one base substitution in ES5, encoding phosphatidylserine synthase (PSS) family protein, which is involved in the base-exchange type reaction to synthesize the minor membrane phospholipid phosphatidylserine. Functional complementation of ES5 in the es5 plants completely restored the wild-type phenotype. Ultra-high-performance liquid chromatography (UHPLC) analysis showed that es5 plants had increased levels of phosphatidylserine (PS) and decreased level of phosphatidylcholine (PC). These results provide evidence about the role of PS in rice leaf senescence.

中文翻译：

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ES5参与调节磷脂酰丝氨酸的合成并影响水稻（Oryza sativa L.）的早期衰老。

影响水稻植物生长和产量的叶片衰老是作物改良的理想目标，并且已经在识别该过程的基础方面取得了显着进展。我们已经表征了水稻中的早期衰老突变体es5（早期叶片衰老5），该水稻在4叶期后表现出叶黄变表型。活性氧（ROS）和丙二醛（MDA）的积累较高，叶绿体解体，叶绿素含量和光合速率降低以及衰老相关基因（SAG）（例如Osh36，OsI57，和OsI85。位置克隆表明es5表型是ES5中一个碱基取代的结果，该碱基编码磷脂酰丝氨酸合酶（PSS）家族蛋白，其参与碱基交换型反应以合成次要膜磷脂磷脂酰丝氨酸。es5植物中ES5的功能互补可完全恢复野生型表型。超高效液相色谱（UHPLC）分析表明，es5植物的磷脂酰丝氨酸（PS）水平升高，而磷脂酰胆碱（PC）水平降低。这些结果提供了有关PS在水稻叶片衰老中的作用的证据。