A Novel Protein RLS1 with NB-ARM Domains Is Involved in Chloroplast Degradation during Leaf Senescence in Rice
A Novel Protein RLS1 with NB-ARM Domains Is Involved in Chloroplast Degradation during Leaf Senescence in Rice
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DOI：
10.1093/mp/ssr081
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发表时间：
2012-01-01
期刊：
影响因子：
27.5
通讯作者：
He, Zu-Hua
中科院分区：
文献类型：
--
作者：
Jiao, Bin-Bin;Wang, Jian-Jun;He, Zu-Hua
叶片衰老是一种以叶绿素降解为特征的细胞程序性死亡，对植物生长和作物生产具有重要意义。自噬参与了叶片衰老过程中叶绿体的降解。然而，该过程中涉及的分子机制尚未得到很好的理解。本研究对水稻rls 1（rapid leaf senescence 1）突变体的遗传和生理特性进行了鉴定。rls1突变体产生了类似疾病的小的黄褐色病变，散布在叶片的整个表面上，比野生型植物显示出更早的衰老。叶片衰老过程中叶绿素含量的迅速丧失是rls 1叶片加速衰老的主要原因。显微镜观察表明，PCD的失调，可能是导致加速降解的叶绿体在rls 1叶片。基于图位克隆的RLS1基因显示，它编码一个以前未知的NB（核苷酸结合位点）的蛋白质与ARM（犰狳）结构域的羧基末端。与其参与叶片衰老相一致，RLS1在黑暗诱导的叶片衰老过程中上调，细胞分裂素下调。有趣的是，RLS1的组成型表达也略微加速了转基因水稻植株的叶片衰老，降低了叶绿素含量。我们的研究确定了一个以前未知的NB-ARM蛋白参与PCD在植物生长和发育过程中，解剖可能的自噬介导的PCD在植物衰老过程中提供了一个独特的工具。
Leaf senescence, a type of programmed cell death (PCD) characterized by chlorophyll degradation, is important to plant growth and crop productivity. It emerges that autophagy is involved in chloroplast degradation during leaf senescence. However, the molecular mechanism(s) involved in the process is not well understood. In this study, the genetic and physiological characteristics of the rice rls1 (rapid leaf senescence 1) mutant were identified. The rls1 mutant developed small, yellow-brown lesions resembling disease scattered over the whole surfaces of leaves that displayed earlier senescence than those of wild-type plants. The rapid loss of chlorophyll content during senescence was the main cause of accelerated leaf senescence in rls1. Microscopic observation indicated that PCD was misregulated, probably resulting in the accelerated degradation of chloroplasts in rls1 leaves. Map-based cloning of the RLS1 gene revealed that it encodes a previously uncharacterized NB (nucleotide-binding site)-containing protein with an ARM (armadillo) domain at the carboxyl terminus. Consistent with its involvement in leaf senescence, RLS1 was up-regulated during dark-induced leaf senescence and down-regulated by cytokinin. Intriguingly, constitutive expression of RLS1 also slightly accelerated leaf senescence with decreased chlorophyll content in transgenic rice plants. Our study identified a previously uncharacterized NB-ARM protein involved in PCD during plant growth and development, providing a unique tool for dissecting possible autophagy-mediated PCD during senescence in plants.