A Single Nucleotide Mutation of the IspE Gene Participating in the MEP Pathway for Isoprenoid Biosynthesis Causes a Green-Revertible Yellow Leaf Phenotype in Rice
A Single Nucleotide Mutation of the IspE Gene Participating in the MEP Pathway for Isoprenoid Biosynthesis Causes a Green-Revertible Yellow Leaf Phenotype in Rice
复制标题
参与类异戊二烯生物合成 MEP 途径的 IspE 基因的单核苷酸突变导致水稻出现绿色可恢复的黄叶表型
DOI：
10.1093/pcp/pcy108
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发表时间：
2018-09-01
影响因子：
4.9
通讯作者：
Deng, Xiaojian
中科院分区：
文献类型：
--
作者：
Chen, Nenggang;Wang, Pingrong;Deng, Xiaojian
植物类异戊二烯依赖于两个独立的途径，即胞质甲基戊酸（MVA）途径和塑性甲基赤藓糖醇磷酸（MEP）途径。IspE是MEP途径中已知的七种酶之一。目前，水稻中还没有发现IspE基因。此外，还没有关于影响MEP通路的基因突变导致翠绿突变的报道。在这项研究中，我们从水稻中分离到了一个绿色可逆性黄叶突变体gry340。突变体表现出光合色素水平降低，黄色叶片中叶绿体和线粒体发育受阻。基于图谱的克隆揭示了gry340突变株中OsIspE的一个错义突变（LOC_Os01g58790）。OsIspE在所有组织中均有组成性表达，其编码蛋白以叶绿体为靶点。此外，通过引入野生型基因，挽救了gry340的突变表型。因此，我们通过图谱克隆成功地鉴定了单子叶植物中的IspE基因，并证实了gry340的绿色可逆黄叶表型是由IspE基因的单核苷酸突变引起的。此外，IspE - IspF双突变体表现出黄化致死表型，表明来自细胞质的类异戊二烯前体不能有效补偿水稻叶绿体中MEP途径的缺陷。实时定量逆转录pcr结果表明，OsIspE的这一功能缺陷不仅影响了其他MEP途径基因的表达，还影响了MVA途径基因、光合基因和线粒体基因的表达。
Plant isoprenoids are dependent on two independent pathways, the cytosolic mevalonate (MVA) pathway and the plastidic methylerythritol phosphate (MEP) pathway. IspE is one of seven known enzymes in the MEP pathway. Currently, no IspE gene has been identified in rice. In addition, no virescent mutants have been reported to result from a gene mutation affecting the MEP pathway. In this study, we isolated a green-revertible yellow leaf mutant gry340 in rice. The mutant exhibited a reduced level of photosynthetic pigments, and an arrested development of chloroplasts and mitochondria in its yellow leaves. Map-based cloning revealed a missense mutation in OsIspE (LOC_Os01g58790) in gry340 mutant plants. OsIspE is constitutively expressed in all tissues, and its encoded protein is targeted to the chloroplast. Further, the mutant phenotype of gry340 was rescued by introduction of the wild-type gene. Therefore, we have successfully identified an IspE gene in monocotyledons via map-based cloning, and confirmed that the green-revertible yellow leaf phenotype of gry340 does result from a single nucleotide mutation in the IspE gene. In addition, the IspE IspF double mutant displayed an etiolation lethal phenotype, indicating that the isoprenoid precursors from the cytosol cannot efficiently compensate for the deficiency of the MEP pathway in rice chloroplasts. Furthermore, real-time quantitative reverse transcription-PCR suggested that this functional defect in OsIspE affected the expression of not only other MEP pathway genes but also that of MVA pathway genes, photosynthetic genes and mitochondrial genes.