水稻类病变突变体 g303的鉴定和基因定位

摘要

The lesion mimic mutant g303 and g342 were isolated by treating the seeds of indica varieties 93 1 1 and R801 5 with γ-ray radiation,respectively.The yellow spots initially appear on g303 leaves at 4-leaf stage.With the growth and development of the plant,the lesions almost occupied the whole plant till the maturity stage.Compared with the wild type,the plant height,seed setting rate and 1000-grain weight of g303 significantly dropped,the chlorophyll and photosynthetic rate obviously decreased.Genetic analysis showed that the mutant phenotype was controlled by a single recessive gene.Using F2 mapping population of g303/ Nipponbare,the g303 mutant gene was mapped between marker InD10 and InD12 on rice chromosome 12,with genetic distances of 0.1 9 cM and 0.76 cM, respectively.Sequence analysis revealed that the mutated gene was allelic to SL ,g303 and g342 mutated gene had a single nucleotide deletion (T572 and G1206,respectively),leading to a premature termination codon.Real-time PCR analysis showed that the expression level of defense-related genes upregulated significantly,these results demonstrated that the mutation may activate the defense response.%通过γ射线辐射诱变籼稻9311和中恢8015分别获得了2个类病变突变体 g303和 g342.g303播种4~5周叶片开始出现黄褐色斑点.随着植株的生长发育,至成熟期病斑几乎布满整个植株.与野生型相比,突变体 g303株高、结实率、千粒重显著下降,叶绿素含量、光合速率显著降低.遗传分析表明,g303类病变性状由一对隐性基因控制.利用 g303/日本晴 F2群体进行定位,将突变基因定位于第12染色体标记 InD10和 InD12之间,遗传距离分别为0．19 cM 和0．76 cM.测序分析发现,该基因与 SL 基因等位,其中 g303和 g342分别在编码区第572位和第1206位发生单碱基缺失,导致翻译提前终止.实时 RT-PCR 结果显示抗病相关基因在突变体 g303中表达量显著上升,说明该基因突变很可能激活了防卫反应.