Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, 350002 Fuzhou, China.
Int J Mol Sci. 2019 Sep 19;20(18):4635. doi: 10.3390/ijms20184635.
RNA editing in plant mitochondria and plastids converts specific nucleotides from cytidine (C) to uridine (U). These editing events differ among plant species and are relevant to developmental stages or are impacted by environmental conditions. Proteins of the MORF family are essential components of plant editosomes. One of the members, MORF9, is considered the core protein of the editing complex and is involved in the editing of most sites in chloroplasts. In this study, the phenotypes of a T-DNA insertion line with loss of and of the genetic complementation line of were analyzed, and the editing efficiencies of plastid RNAs in roots, rosette leaves, and flowers from the mutant and the wild-type (WT) control were compared by bulk-cDNA sequencing. The results showed that most of the known -associated plastid RNA editing events in rosette leaves and flowers were similarly reduced by mutation, with the exception that the editing rate of the sites and declined in the leaves and that of decreased only in the flowers. In the roots, however, the loss of MORF9 had a much lower effect on overall plastid RNA editing, with nine sites showing no significant editing efficiency change, including , , , , , , and , which were reduced in the other tissues. Furthermore, we found that during plant aging, mRNA level, but not the protein level, was downregulated in senescent leaves. On the basis of these observations, we suggest that MORF9-mediated RNA editing is tissue-dependent and the resultant organelle proteomes are pertinent to the specific tissue functions.
RNA 编辑在植物的线粒体和质体中将特定的胞嘧啶 (C) 转化为尿嘧啶 (U)。这些编辑事件在植物物种之间存在差异，与发育阶段相关，或受环境条件影响。MORF 家族的蛋白质是植物编辑体的重要组成部分。其中一个成员，MORF9，被认为是编辑复合物的核心蛋白，参与了大多数叶绿体位点的编辑。在这项研究中，分析了 T-DNA 插入缺失突变体和 的遗传互补系的表型，并通过 bulk-cDNA 测序比较了根、莲座叶和花中突变体和野生型 (WT) 对照的质体 RNA 的编辑效率。结果表明，除了 位点在叶片中的编辑率下降，而 在花朵中的编辑率仅下降外，大多数在莲座叶和花朵中与 相关的质体 RNA 编辑事件都因 突变而显著减少，除了在叶片中， 位点的编辑率下降，而在花朵中仅下降。然而，在根部，MORF9 的缺失对整体质体 RNA 编辑的影响要小得多，有九个位点的编辑效率没有明显变化，包括 、 、 、 、 、 、 ，这些在其他组织中减少。此外，我们发现，在植物衰老过程中，衰老叶片中的 mRNA 水平而非蛋白水平下调。基于这些观察，我们认为 MORF9 介导的 RNA 编辑是组织依赖性的，由此产生的细胞器蛋白质组与特定的组织功能相关。
