Liu Xi, Xu Ziyi, Yang Yanrong, Cao Penghui, Cheng Hang, Zhou Haiying
Key Laboratory of Eco-Agricultural Biotechnology around Hongze Lake, Regional Cooperative Innovation Center for Modern Agriculture and Environmental Protection, Huaiyin Normal University, Huai'an, 223300, China.
Suzhou Academy of Agricultural Sciences, Suzhou, 215155, China.
Rice (N Y). 2021 May 20;14(1):45. doi: 10.1186/s12284-021-00489-6.
Plant plastidic caseinolytic protease (Clp) is a central part of the plastid protease network and consists of multiple subunits. The molecular functions of many Clps in plants, especially in crops, are not well known.
In this study, we identified an albino lethal mutant al3 in rice, which produces albino leaves and dies at the seedling stage. Molecular cloning revealed that AL3 encodes a plastid caseinolytic protease, OsClpR1, homologous to Arabidopsis ClpR1 and is targeted to the chloroplast. Compared with the wild type, chloroplast structure in the al3 mutant was poorly developed. OsClpR1 was constitutively expressed in all rice tissues, especially in young leaves. The OsClpR1 mutation affected the transcript levels of chlorophyll biosynthesis and chloroplast development-related genes. The RNA editing efficiency of three chloroplast genes (rpl2, ndhB, ndhA) was remarkably reduced in al3. Using a yeast two-hybrid screen, we found that OsClpR1 interacted with OsClpP4, OsClpP5, OsClpP2, and OsClpS1.
Collectively, our results provide novel insights into the function of Clps in rice.
植物质体酪蛋白水解蛋白酶（Clp）是质体蛋白酶网络的核心组成部分，由多个亚基组成。许多植物Clp的分子功能，尤其是作物中的Clp，尚不为人所知。
在本研究中，我们在水稻中鉴定出一个白化致死突变体al3，其产生白化叶片并在幼苗期死亡。分子克隆表明，AL3编码一种与拟南芥ClpR1同源的质体酪蛋白水解蛋白酶OsClpR1，并定位于叶绿体。与野生型相比，al3突变体中的叶绿体结构发育不良。OsClpR1在所有水稻组织中组成型表达，尤其是在幼叶中。OsClpR1突变影响了叶绿素生物合成和叶绿体发育相关基因的转录水平。al3中三个叶绿体基因（rpl2、ndhB、ndhA）的RNA编辑效率显著降低。通过酵母双杂交筛选，我们发现OsClpR1与OsClpP4、OsClpP5、OsClpP2和OsClpS1相互作用。
总体而言，我们的结果为水稻中Clp的功能提供了新的见解。
