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叶色突变是一类十分明显的性状突变,在高等植物的叶绿素合成、叶绿体结构、功能、遗传、分化与发育等基础研究中均具有重要意义。到目前为止,已鉴定多个重要的水稻功能基因,据不完全统计,水稻中至少已定位了79个叶色突变位点,并已成功克隆出多个叶色相关基因,其中OsCHLH、OsCAO1、OsCAO2、chlorina1、chlorina9、ygl等直接参与编码叶绿素合成,其余基因均参与叶绿体发育调控。在日本晴(Nipponbare)T-DNA插入突变体库中筛选到一份对温度敏感的白条纹突变体gws(green-white-stripe),遗传分析表明它来自组织培养过程中的单隐性基因突变。利用gws与培矮64杂交组合的F2代群体,将Gws精细定位于第6染色体标记InDel15和InDel16之间,物理距离为73kb,此区间内包含13个基因。基因组序列分析发现,突变体在核糖核苷二磷酸还原酶小亚基(ribonucleoside-diphosphate reductase small chain,RNRS1)编码区第314～315碱基发生缺失,第316～317碱基由GC变为TT,导致该基因阅读框移码突变,蛋白质翻译提前终止。该基因是已经报道的水稻白条纹叶基因St1(Stripe1)的等位基因,gws突变体较st1突变体的白条纹出现早且明显,gws白条纹表型出现在第2片叶之后,而st1的白条纹表型仅出现在第4或5片叶之后。
Leaf color mutation is a very obvious trait mutation, which is of great significance in the basic research of chlorophyll synthesis, chloroplast structure, function, genetics, differentiation and development of higher plants. So far, a number of important rice functional genes have been identified. According to incomplete statistics, at least 79 leaf color loci have been mapped in rice and many leaf color related genes have been successfully cloned. OsCHLH, OsCAO1, OsCAO2, chlorina1, chlorina9, ygl directly involved in coding chlorophyll synthesis, the rest of the genes are involved in the regulation of chloroplast development. A temperature-sensitive white-streak mutant gws (green-white-stripe) was screened from Nipponbare T-DNA insertion mutants and genetic analysis indicated that it was derived from a single recessive gene mutation during tissue culture. Using F2 population of gws and Pei’ai 64 hybrids, Gws was finely mapped between chromosome 6 markers InDel15 and InDel16 on chromosome 6 with a physical distance of 73kb and 13 genes in this interval. Genomic sequence analysis revealed that the mutants were deleted from the 314th to 315th nucleotides in the coding region of ribonucleoside-diphosphate reductase small chain (RNRS1), while the 316th to 317th bases changed from GC to TT , Leading to frameshift mutation of the gene reading frame and early termination of protein translation. This gene is an allele of St1 (Stripe1) which has been reported in rice leaf streaks. The streaks of gws mutants appear earlier and more obvious than st1 mutants, and the streaks of white streaks appear after the second leaf The white stripe phenotype appears only after the 4th or 5th leaf.