Resistance Analysis Of Widely-Grown Soybean Cultivars To Phytophthora Root Rot In Huang-Huai-Hai Rivers Valley

With the application of wheat stubble no-tillage cultivation technology,the occurrence rate of phytophthora root rot of soybean is getting higher in the Huang-Huai-Hai Rivers Valley.Therefore,it is crucial to investigate the resistances of the widely-grown soybean cultivars to phytophthora root rot and to screen disease-resistant resources for soybean improvement.Soybean and Phytophthora sojae were typical of gene for gene relationships,so gene postulation method can be used to identify resistance gene in widely-grown soybean cultivars preliminarily.A genome-wide scan of the major cultivars was carried out using the SSR markers closely linked to the known resistance genes to obtain the excellent loci,alleic variation and vector cultivars associated with phytophthora resistance.The main results were as follows:?1?In the current study,a total of 140 soybean cultivars,widely-grown in Huang-Huai-Hai Rivers Valley since the 1950 s,were investigated for their response to eight strains of Phytophthora sojae through the hypocotyls inoculation method.The results showed that 6 cultivars were susceptible to all eight strains,and 134 or 95.7% of the identified cultivars were resistant to one to eight strains of Phytophthora sojae.Among the cultivars,83 or 59.3% were resistant to more than six Phytophthora sojae strains,and showed 65 reaction types identified by comparing with the reaction types of 14 reference cultivars.Five reaction types produced by 19 cultivars were the same as known single gene or two gene combinations,and 60 reaction types produced by 115 cultivars were different from the reaction types controlled by the known single gene or two gene combinations,suggesting that there were novel resistant genes or gene combinations.?2?A total genome of 140 widely-grown soybean cultivars was screened by 104 SSR markers,genetic diversity and population structures were analyzed.Based on this,Tassel 3.0 software GLM and MLM were used to locus the resistance to Phytophthora sojae.The allelic variability of the allele was further analyzed by using the mean value of the “ineffective allele” cultivars,a total of 337 alleles were detected,the variation range from 2 to 7,and the diversity ranged from 0.112 to 0.802,the diversity information content ranged from 0.101 to 0.775.?3?The subspecies were divided into three subgroups through population structures analysis: the first subgroup had 14 varieties,the second subgroup had 42 varieties,and the third subgroup had 84 varieties.?4?By two kinds of association analysis model,are associated with Phytophthora sojae Ps41-1 resistance loci of Sat₂22;associated with PsJS2 resistance locus Satt009;associated with PsRace4 resistance loci were Satt241,Satt304,Satt683 and Satt288;associated with PsRace5 resistance loci of Satt418 and Satt288;associated with PsMC1 resistance loci of Satt009 and associated with PsUSAR2 resistance locus was Satt448.?5?Identification of Satt009-5 and other resistant to phytophthora root rot of elite alleles of loci,and Hedou20 and other carriers to excellent cultivars.