中文摘要：

【目的】对水稻白化转绿突变体gra75（green-revertible albino 75）进行基因定位,并对其生理特性进行分析。【方法】利用EMS处理粳稻品种日本晴（Nipponbare）的迟熟突变体10079,从后代中获得一个白化转绿突变体gra75。对该突变体的形态特征、生理特性及主要农艺性状进行观察与分析,并应用（gra75/浙辐802）的F2群体精细定位目标基因,遴选候选基因。【结果】gra75突变体叶片从第4叶开始表现出白化性状,从第8叶开始恢复到正常绿色,之前白化的叶片也会逐渐转为淡绿色,成熟期主要农艺性状与野生型没有明显的差异。突变体苗期白化叶的叶绿素和类胡萝卜素含量显著下降,叶肉细胞中叶绿体数目减少,并且叶绿体形态发育不饱满,类囊体片层、基粒和淀粉粒数目减少。遗传分析表明该性状是由1对隐性核基因控制,该基因位于第6染色体短臂InDel标记HC1和HC2之间,遗传距离分别为0.06 cM和0.6 cM,物理距离为120 kb。对该区域候选基因分析和测序,发现LOC_Os06g07210基因（编码核糖核苷酸还原酶大亚基RNRL1）在编码区第716位碱基C突变成T,导致其编码蛋白第239位的丙氨酸（Ala）突变成缬氨酸（Val）。【结论】gra75突变体基因与已报道的水稻淡绿叶基因V3（Virescent3）为等位基因,但gra75突变体苗期的白化转绿性状能稳定表达,且白化表型对后期的主要农艺性状影响不显著,故该突变基因作为叶色标记基因在水稻遗传育种中具有较大的应用价值。

英文摘要：

[Objective] On the basis ofphenotypic and physiological characteristics of a green-revertible albino mutant gra75, the mutant gene was finely mapped. [Method] A green-revertible albino mutant was isolated from ethyl methanesulfonate mutagenesis. Phenotypes of the mutant were observed, and its physiological characteristics and main agronomic traits were analyzed. Genetic mapping of the mutant gene was conducted by using molecular marker and F2 mapping population of gra75/Zhefu 802 to identify this candidate gene. [Result] Under paddy field conditions, gra75 mutant plants exhibited a normal green phenotype up to the third-leaf stage. Subsequently, it produce albino phenotype during the fourth to seventh leaf stage, but then it developed nearly normal green leaves from the eighth-leaf stage. At the mature stage, the gra75 mutant and its wild-type had no significant difference in major agronomic traits. On the other hand, chlorophyll and carotenoid content in albino leaves of the mutant obviously decreased at seedling stage. Electron microscopic observation revealed that the number of chloroplasts, thylakoid membranes, granums and starch granules significantly decreased in mesophyll cells of the albino leaves. Genetic analysis suggested that the mutant phenotype ofgra75 was controlled by one recessive nuclear gene. The gra75 mutant gene was mapped between InDel markers HC 1 and HC2 on the short ann of rice chromosome 6, with genetic distances of 0.06 cM and 0.6 cM, respectively, and with a physical interval of 120 kb. By analyzing and sequencing the candidate genes in this genomic region, it was found that there was a single nucleotide change （C716T） in exon 5 of LOC_Os06g07210 gene encoding RNRL1 （ribonucleotide reductase large subunit） in the gra75 mutant, which caused a missense mutation （Ala to Val） in the encoded product. [Conclusion] The gra75 mutant gene was allelic to I13 （Virescent3） gene. However, the green-revertible albino character of gra75 mutant could express steadily at seedling stage,