Pi-b和Pi-ta基因在江苏省粳稻中的分布以及与穗颈瘟抗性的关系

Distribution of Pi-b and Pi-ta genes in japonica rice of Jiangsu province and their relationship with neck blast resistance

利用稻瘟病抗性基因Pi-b、Pi-ta等位基因的显性标记对48份江苏省粳稻品种和618份粳稻新品系进行检测,并结合6个代表性稻瘟病生理小种的穗颈瘟抗性鉴定反应,分析抗性基因在江苏省粳稻中的分布及其与穗颈瘟抗性的关系。结果显示:抗性基因Pi-b和Pi-ta在江苏省粳稻品种和品系中存在广泛分布,其中抗性基因Pi-b的频率明显高于Pi-ta。不同生育类型的品种中,抗性基因Pi-b和Pi-ta在中熟中粳中的分布最少,且pi-b/pi-ta基因组合品种所占比例最高。从基因组合与抗性的关系来看,含单个抗性基因的新品系无论是感病率还是病情指数都明显低于不含Pi-b和Pi-ta抗性基因的品系,且Pi-ta基因的抗性效果要好于Pi-b基因,而同时含有两个抗性基因的新品系其抗性水平又优于只含单个抗性基因的粳稻品系。因此,在育种中选择两个抗性基因互补的粳稻作亲本,在后代群体中进行基因聚合,是提高江苏省粳稻穗颈瘟抗性最快速、有效的方法。

To figure out the distribution of Pi-b and Pi-ta genes in japonica rice of Jiangsu province and their relationship with neck blast resistance,48 japonica varieties and 618 japonica lines were detected using dominant markers of Pi-b and Pi-ta alleles,together with the evaluation of resistance for rice neck blast inoculated with 6 physiological races.The results showed that the Pi-b and Pi-ta genes were widespread in the japonica rice varieties and lines,and the frequency of Pi-b was higher than that of Pi-ta. The middle maturity medium japonica varieties presented the least number of Pi-b and Pi-ta genes. The pi-b / pi-ta gene combination accounted for the largest percentage in all varieties. The relationship between gene distribution and resistance revealed that the susceptible rate and disease index of new lines with either Pi-b or Pi-ta were lower than those without Pi-b and Pi-ta genes,and Pi-ta gene showed stronger effect than Pi-ta. Meanwhile,the resistance performance of lines carrying both genes was better than the lines with either gene. Therefore,selecting complementary varieties with the two resistance genes as parents to realize gene pyramiding is the most rapid and effective way to improve neck blast resistance of japonica rice.