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利用EMS处理浙粳22种子,从突变体库中筛选获得了1个水稻类病变突变体T34。T34突变体从3叶期开始在叶片及叶鞘出现橘红色斑块,并随着生长发育可布满整个植株;类病斑的形成不受温度的影响。组织化学染色分析显示T34表现为细胞自主性死亡的坏死病斑。T34突变体对2个白叶枯病菌小种的抗性显著增强。遗传分析表明,T34类病变性状由1对隐性基因控制。以T34突变体与籼稻9311杂交的F2分离群体作为定位群体,将突变基因定位在12号染色体短臂上着丝点附近分子标记STS-12-50和STS-12-34之间的360 kb区域内。测序分析发现,该基因与SL基因等位,在编码区第673位碱基G突变成T,导致其蛋白225-天冬氨酸突变成225-酪氨酸,与已报道的sl/spl1突变体SL基因突变位点均不同。生物信息学方法分析发现T34突变体SL蛋白三级结构与野生型的存在较大差异,推测这一单碱基突变导致了类病变性状的发生。
A strain of rice mutant T34 was screened from the mutant library by EMS treatment. The T34 mutant displayed orange-red patches in the leaves and sheaths from the third leaf stage and covered the entire plant with the growth and development. The formation of the lesion-like spots was not affected by temperature. Histochemical staining showed that T34 showed necrotic lesion of autophagic cell death. The resistance of T34 mutants to two bacterial leaf blight races was significantly enhanced. Genetic analysis showed that T34-like lesions were controlled by one recessive gene. The F2 segregating population of crosses between T34 mutant and indica 9311 was used as the loci. The mutant gene was located on the short arm of chromosome 12 in the 360 kb region between molecular markers STS-12-50 and STS-12-34 Inside. Sequencing analysis showed that this gene was allelic to the SL gene and the base G at position 673 of the coding region was mutated to T, resulting in the mutation of its protein 225-aspartate to 225-tyrosine. Compared with the previously reported SL / spl1 mutant SL gene mutation sites are different. Bioinformatics analysis showed that T34 mutant SL protein tertiary structure and wild-type there is a big difference, suggesting that this single-base mutation led to the occurrence of similar lesions.