Uncovering Divergence of Rice Exon Junction Complex Core Heterodimer Gene Duplication Reveals Their Essential Role in Growth, Development, and Reproduction
Uncovering Divergence of Rice Exon Junction Complex Core Heterodimer Gene Duplication Reveals Their Essential Role in Growth, Development, and Reproduction
复制标题
揭示水稻外显子连接复合体核心异二聚体基因复制的分歧揭示了它们在生长、发育和繁殖中的重要作用。
DOI：
10.1104/pp.114.237958
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发表时间：
2014-07-01
期刊：
影响因子：
7.4
通讯作者：
He, Chaoying
中科院分区：
文献类型：
--
作者：
Gong, Pichang;He, Chaoying
外显子连接复合体(EJC)在动物体内具有重要的发育作用，但在植物中的作用尚不清楚。在这里，我们展示了每个重复的Mago Nashi(Mago)和Y14基因对在水稻(Oryza Sativa)中编码可能形成专有的Mago-Y14异源二聚体的EJC核心亚单位的不同方面的差异。OsMAGO1、OsMAGO2和OsY14a在所有组织中都有成分表达，而OsY14b主要在胚胎组织中表达。OsMAGO2和OsY14b对不同胁迫的敏感性高于OsMAGO1和OsY14a，其编码蛋白对的同源性分别为93.8%和46.9%。在水稻中，单基因MAGO的下调没有导致任何表型变异，但双基因敲除产生了开花异常的矮秆水稻植株，这些花的雄蕊对药室内壁和绒被层的降解和吸收都受到抑制，这表明OsMAGO1和OsMAGO2是功能冗余的。OsY14a基因敲除了表型复制的OsMAGO1OsMAGO2突变体，而OsY14b的下调未能诱导出植株，这表明OsY14b在胚胎发生中具有功能专一性。OsMAGO1OsMAGO2OsY14a三重下调增强了OsMAGO1OsMAGO2和OsY14a下调突变体的表型，表明它们在MAGO-Y14异源二聚模式中发挥发育作用。在这些基因敲除的发育途径中发现了基因表达的改变，而雄蕊发育的关键调控因子未发育的TAPETUM1(OsUDT1)的转录剪接是唯一异常的。同时，Mago和Y14选择性地与OsUDT1前信使RNA结合，表明水稻EJC亚基调控剪接。我们的工作为被子植物中EJC基因在生长、发育和繁殖中的功能提供了新的见解，并暗示了这些基因在谷物适应性进化中的作用。
The exon junction complex (EJC) plays important developmental roles in animals; however, its role in plants is not well known. Here, we show various aspects of the divergence of each duplicated MAGO NASHI (MAGO) and Y14 gene pair in rice (Oryza sativa) encoding the putative EJC core subunits that form the obligate MAGO-Y14 heterodimers. OsMAGO1, OsMAGO2, and OsY14a were constitutively expressed in all tissues, while OsY14b was predominantly expressed in embryonic tissues. OsMAGO2 and OsY14b were more sensitive to different stresses than OsMAGO1 and OsY14a, and their encoded protein pair shared 93.8% and 46.9% sequence identity, respectively. Single MAGO down-regulation in rice did not lead to any phenotypic variation; however, double gene knockdowns generated short rice plants with abnormal flowers, and the stamens of these flowers showed inhibited degradation and absorption of both endothecium and tapetum, suggesting that OsMAGO1 and OsMAGO2 were functionally redundant. OsY14a knockdowns phenocopied OsMAGO1OsMAGO2 mutants, while down-regulation of OsY14b failed to induce plantlets, suggesting the functional specialization of OsY14b in embryogenesis. OsMAGO1OsMAGO2OsY14a triple down-regulation enhanced the phenotypes of OsMAGO1OsMAGO2 and OsY14a down-regulated mutants, indicating that they exert developmental roles in the MAGO-Y14 heterodimerization mode. Modified gene expression was noted in the altered developmental pathways in these knockdowns, and the transcript splicing of UNDEVELOPED TAPETUM1 (OsUDT1), a key regulator in stamen development, was uniquely abnormal. Concomitantly, MAGO and Y14 selectively bound to the OsUDT1 premessenger RNA, suggesting that rice EJC subunits regulate splicing. Our work provides novel insights into the function of the EJC locus in growth, development, and reproduction in angiosperms and suggests a role for these genes in the adaptive evolution of cereals.