A single nucleotide mutation of IspF gene involved in the MEP pathway for isoprenoid biosynthesis causes yellow-green leaf phenotype in rice
A single nucleotide mutation of IspF gene involved in the MEP pathway for isoprenoid biosynthesis causes yellow-green leaf phenotype in rice
复制标题
类异戊二烯生物合成 MEP 途径中涉及的 IspF 基因的单核苷酸突变导致水稻黄绿色叶片表型
DOI：
10.1007/s11103-017-0668-7
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发表时间：
2018-01-01
影响因子：
5.1
通讯作者：
Deng, Xiaojian
中科院分区：
文献类型：
--
作者：
Huang, Rui;Wang, Yang;Deng, Xiaojian
类异戊二烯是所有生物中最丰富的天然化合物，其来源于基本的五碳单元异戊烯基二磷酸（IPP）和二甲基烯丙基二磷酸（DMAPP）。在植物中，IPP和DMAPP通过两条独立的途径合成，即细胞质中的甲羟戊酸途径和质体中的2-C-甲基-d-d4-磷酸（MEP）途径。MEP途径包括七个酶促步骤，其中IspF是第五个酶。到目前为止，还没有在单子叶植物中鉴定出IspF基因。在本研究中，我们从水稻（Oryza sativa）中分离到一个叶色突变体505 ys。该突变体表现出黄绿叶表型，光合色素水平降低，叶绿体发育受阻。通过对该突变体的图位克隆，我们发现OsIspF基因（LOC_Os02g45660）与拟南芥的IspF基因具有显著的相似性，但突变体中发生了错义突变，导致编码蛋白的氨基酸发生了改变。OsIspF基因在所有检测组织中均有表达，其编码蛋白定位于叶绿体。此外，通过用野生型OsIspF基因转化来补充505 ys的突变表型。因此，我们成功地在单子叶植物中鉴定了IspF基因。此外，实时荧光定量RT-PCR结果表明，OsIspF基因与MEP途径的其他酶基因和叶绿素合成酶基因之间存在正调控关系。同时，这也表明参与MEP途径的单个基因可能对光合作用相关基因的表达水平具有差异调节作用。
Isoprenoids are the most abundant natural compounds in all organisms, which originate from the basic five-carbon units isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). In plants, IPP and DMAPP are synthesized through two independent pathways, the mevalonic acid pathway in cytoplasm and the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway in plastids. The MEP pathway comprises seven enzymatic steps, in which IspF is the fifth enzyme. So far, no IspF gene has been identified in monocotyledonous plants. In this study, we isolated a leaf-color mutant, 505ys, in rice (Oryza sativa). The mutant displayed yellow-green leaf phenotype, reduced level of photosynthetic pigments, and arrested development of chloroplasts. By map-based cloning of this mutant, we identified OsIspF gene (LOC_Os02g45660) showing significant similarity to IspF gene of Arabidopsis, in which a missense mutation occurred in the mutant, resulting in an amino acid change in the encoded protein. OsIspF gene was expressed in all tissues detected, and its encoded protein was targeted to the chloroplast. Further, the mutant phenotype of 505ys was complemented by transformation with the wild-type OsIspF gene. Therefore, we successfully identified an IspF gene in monocotyledonous plants. In addition, real-time quantitative RT-PCR implied that a positive regulation could exist between the OsIspF gene and the genes encoding other enzymes of the MEP pathway and chlorophyll synthase. At the same time, it also implied that the individual genes involved in the MEP pathway might differentially regulated expression levels of the genes associated with photosynthesis.