Distribution And Application Of Two Blast Resistant Genes Pita And Pib In Landrace Rice In China

Genetic diversity provides a wealth of material for breeding. So that we can breednew cultivars carring certain traits which we need. We can reduce the breedingpro-blindness and improve breeding efficiency by analyzing the genetic diversity oflandrace rices and choosing the hybrid combination with strong advantage depend onthe genetic distance.The rice blast is one of the three major diseases of rice, is also a limit factor to highand stable yield of rice. In which, the hazards caused by neck blast are the mostserious. Breeding and cutilizing resistant cultivars are the most effective, safe andeconomical way of controlling blast disease. Exploring the anti-source and appraisingresistance genes are the basis and prerequisite to cultivate disease-resistant varieties.Marker-assisted selection is an effective means of resistance genes appraising.In this study, the genetic diversity of115landrace rices was analyzed with74pairsof SSR primers. Functional markers of blast resistance genes Pita、Pib were used todetect115landrace rice and part of Japonica rice lines in Jiangsu provinceintermediate experiment of2009and2010years. Combing with the blast resistanceresults, the value of Pita、Pib in Jiangsu province Japonica rice neck blast resistancewas analyzed by correlation analysis. The main results are as follows:1.266alleles were detected by74SSR markers. The average number ofalleles perlocus was3.595with a range f rom2to7. The average PIC is0.576,ranged from0.115to0.793.Cluster analysis results showed that the similarity coefficient svariedfrom0.552to0.928and UPGMA cluster analysis showed that the rice landraces testedcould be divided into2groups(Japonica and Indica) at a genetic similarity coefficientof0.621. Genetic diversity of these landrace rices is quite rich. There are somegenetic differences between varieties are on different regions. Some varieties from thesame region are often get together, that their genetic background close，while somevarieties from the same region are disperse in clustering chart, that their geneticbackground far.2. The Pita resistant allele distribute widely in china including Zhejiang Province，Fujian Province，Guangdong Province，Guangxi Province，Sichuan Province，GuizhouProvince，Anhui Province，Jiangxi Province，Henan Province，Hebei Province，JilinProvince，but not found in Jiangsu Province，Shandong Province，Hunan Province，Hubei Province and Shanghai City. Only two landrace harbored the Pib resistant allele．3.11cultivars harbored Pita resistant allele and8cultivars harbored Pib resistantallele. Interestingly, the8cultivars harboring Pib carried the Pita resistant allelesimultaneously．4. Pita and Pib were positively correlated with neck blast resistance of Japonicarice in Jiangsu province. The correlation coefficients of Pita were0.5and0.37respectively in two years as the correlation coefficients of Pib were0.55and0.51.The correlation coefficients of two genes joint effect were0.71and0.62respectively.Therefore, carrying both of this two resistance genes can greatly improve theresistance of Japonica rice in Jiangsu province.