水稻淡黄叶突变体pyl3的鉴定和基因定位

利用⁶⁰Co-γ辐射诱变籼稻骨干恢复系川恢907(R907),从突变体库中筛选获得一份淡黄叶突变体pyl3 (pale yellow leaf mutant 3)。为揭示pyl3突变体淡黄叶表型的调控机制,本研究对该突变体和野生型进行表型鉴定、主要农艺性状和基因定位分析。结果表明,从苗期开始pyl3突变体整个生育期表现淡黄叶表型;与野生型相比,pyl3在苗期叶片中的叶绿素和类胡萝卜素含量显著降低;成熟期pyl3的株高、穗长、穗粒数和结实率等农艺性状指标均显著下降。遗传分析结果表明,pyl3突变体的表型由一对隐性核基因控制。利用分子标记连锁分析的方法将该基因初步定位于第3号染色体上InDel标记M4和M6之间,物理距离约为3.2 Mb。进一步基于BSA全基因组重测序和Sanger测序分析发现,pyl3突变体在定位区间内编码Mg-原卟啉Ⅸ螯合酶CHLI亚基的基因编码区第1 034位碱基C突变为碱基T,导致编码的第345位的半胱氨酸(Cys)突变为酪氨酸(Tyr)。pyl3突变体中携带的CHLI^pyl3是已报道黄绿叶基因chl9/chli的新等位基因。qRT-PCR分析结果显示,pyl3突变体中叶绿素合成和光合作用相关基因的表达发生变化。本研究为进一步解析CHLI基因调控水稻叶色的分子机制提供了新的遗传材料和理论依据。

Characterization and Gene Mapping of pyl3 Mutant in Rice

A pale yellow leaf 3(pyl3) mutant was isolated from the ⁶⁰Co-γ radiation mutagenized population of indica rice restorer Chuanhui907 (R907). To clarify the regulation mechanism of the pale yellow leaf phenotype in pyl3 mutant, phenotype identification, major agronomic traits and gene mapping analysis were performed in this study. The results showed that pyl3 mutant exhibited a pale yellow leaf phenotype from the seedling stage to mature stage. Chlorophyll and carotenoid contents were significantly reduced in pyl3 leaves at seedling stage and most agronomic traits including plant height, panicle length, grain number per panicle and seed setting rate of pyl3 were significantly decreased at mature stage. Genetic analysis indicated that the phenotype of the pyl3 mutant was controlled by a single recessive nuclear gene. The candidate gene was preliminarily mapped to a 3.2 Mb region between InDel markers M4 and M6 on chromosome 3 by using molecular marker linkage analysis. Further Bulked-Segregant Analysis (BSA) based whole genome resequencing and sanger sequencing analysis showed that a point mutation (C1034T) in the CHLI gene, which encoded the Mg-protoporphyrin Ⅸ chelatase Ⅰ subunit, resulted a substitution of Tyr by Cys at the 345^thposition of the encoding protein, suggesting that the CHLI ^pyl3gene in pyl3 mutant is a novel allele of the chl9/chli gene. Additionally, the qRT-PCR analysis showed that the expression levels of chlorophyll synthesis and photosynthesis related genes were altered in pyl3 mutant. This study provides a new genetic material and theoretical basis for further studying the molecular regulation mechanism in rice leaf color.