辽宁地区粳稻品种抗稻瘟病基因Pita的等位基因类型及其功能研究

Allelic Types and Functions of the Rice Blast Resistance Gene Pita in Japonica Rice Varieties in Liaoning Region

Pita是最早被定位的抗稻瘟病基因之一,并广泛应用于世界各稻区的抗稻瘟病品种选育中。研究不同地区水稻品种中Pita等位基因的类型及其对田间流行病原菌的抗性对于水稻抗病育种具重要意义。本研究选用17份辽宁地区粳稻品种,通过对供试材料的Pita等位基因进行测序,发现该基因在这些品种中只有两种类型(Pita-A,Pita-B),他们之间存在7个单碱基突变(SNP),未发现插入缺失突变,这些突变导致5个氨基酸发生变化,没有导致基因表达的提前终止;通过人工接种鉴定,发现含有Pita-A的水稻抗病率仅为20%,而含有Pita-B的水稻抗病率高达70%,表明Pita-B对辽宁地区稻瘟病菌具一定抗病性,但当将Pita-B克隆并转化于感病品种辽星1号时,转基因T0代植株对同样的病原菌仍表现感病,进而表明单独携带Pita抗病基因的水稻品种对辽宁地区稻瘟病菌抗性较差,在进行抗病品种选育时,需与其它基因聚合使用,以提高品种的广谱抗性。

Pita is one of the plumier cloned rice blast resistance genes. It is widely used in rice blast resistant varieties bleeding in the world. The studies of Pita alleles in different regions and its resistance to local blast isolates are of great significance for rice breeding. We found two alleles, Pita-A and Pita-B, in 17 japonica rice cuhivars. There were 7 single nucleotide mutations （SNP） and no Indel mutation. These nucleotide muta- tions led to five amino acids change and no premature temlination of gene expression. By t^sistance assess- ment, we found that 70% of these varieties carrying Pita-B were resistant to local blast isolates, while only 20% of the varieties that carried Pita-A were resistant to rice blast. We transfommd Pita-B into a susceptible variety Liaoxing 1, and the transgenic TO plants were still susceptible to the same blast isolates. These results show that the rice cultivars only carried Pita are less resistant to blast fungus in Liaoning area. When we breed resistant varieties, it is needed to polymerize pita with other genes to improve the broad spectrum resistance of the rice varieties