水稻类病斑突变体spl31的遗传分析与基因定位

利用EMS诱变水稻籼型恢复系缙恢10号, 从其后代中鉴定出一个类病斑突变体spl31, 该突变体三叶期以前表型正常, 四叶期后叶片陆续出现黄色斑点, 随着植株的生长, 面积逐渐扩大成边缘黄褐色的病斑, 至成熟时病斑相互连接成片, 导致叶片坏死。透射电镜结果显示突变体细胞的叶绿体基粒片层堆叠不规则。组织化学分析显示突变体细胞被染成深蓝色, 呈离散状分布, 说明spl31病斑是自发形成的。光合数据显示spl31基因突变对病斑叶片正常部位细胞的光系统II影响较小。农艺性状分析发现突变体千粒重下降、结实率降低。遗传分析表明, spl31的突变性状由1对隐性核基因控制, 该基因被定位于水稻第12染色体着丝粒附近, 引物ID104和ID11之间, 物理距离为383 kb, 并与标记ID105共分离。

Genetic Analysis and Fine Mapping of a Lesion Mimic Mutant spl31 in Rice

A lesion mimic mutant temporarily designated as spl31 was discovered in the progeny of an excellent indica restorer line Jinhui 10 with seeds treated by ethyl methane sulfonate (EMS). The mutant phenotype was normal before the three leaf period but with yellow bad spots onleaves after the four leaf period. Along with the growth and development of the plant, the number of spots didn’t show significant difference, whereas the lesion area gradually enlarged and developed with tawny margin. As the spl31 matured, lesion spots interconnected between each other becoming a continuous piece, resulting in leaves’ death. The observation by transmission electronic microscope (TEM) demonstrated that most grana lamellae in spl31’s chroloplasts were irregularly stacked. Histochemical analysis revealed that deep blue stained cells presented discrete dietilution, illustrating that the lesion mechanism of spl31 may be spontaneously generated. The photosynthetic data showed that the mutation of spl31 had no effect onPSII. Furthermore, both 1000-grain weight and seed setting rate of the mutant decreased as compared with the wild type. Genetic analysis suggested that spl31 was controlled by a single nuclear recessive gene. Nipponbare was crossed with the spl31 and 621 mutational F₂ recessive plants were used for gene mapping. And finally, Spl31 locus was mapped on chromosome 12 near the centromere between ID104 and ID11 with physical distance of 383 kb and co-segregated with ID105.