| Peanut pod rot is a fungal disease worldwide that directly affects the production and quality of peanut.Establishing effective criteria for disease resistance evaluation and screening,exploring and innovating germplasm resources are the important basis for the disease resistance breeding.At the same time,obtaining molecular markers related to disease resistance using resistance germplasm resources can promote the process of breeding for disease resistance by marker-assisted selection.To explore the excellent peanut germplasm for genetic improvement,77 American and 39 domestic peanut accessions were collected to identify and evaluate peanut pod rot resistance and establish criteria of peanut pod rot resistance by means of injury index and cluster analysis.According to the results of the previous study in our laboratory,the correlation between peanut pod rot resistance and bacterial wilt resistance was found.Twelve pairs of SSR markers related to resistance to peanut bacterial wilt according to references and 48 pairs of InDel markers developed and designed based on the result of stress resistance in our lab were selected to conducted correlation analysis and multiple linear stepwise regression so as to detect SSR and InDel markers associated with peanut pod rot resistance.The main results were as follows:1.One hundred and sixteen accessions of peanut,including 77 American and 39 domestic germplasm,were evaluated in a two-year field experiment in this study.According to the cluster analysis of annual injury index,the resistance to pod rot of peanut was divided into five groups: high resistance(HR)0<INI?25;resistance(R)25<INI?45;medium resistance(MR)45<INI?60;susceptible(S)60<INI?75 and high susceptible(HS)INI>75.2.Of 96 accessions consistent in pod rot resistance in 2 years evaluation,we obtained 2 high resistant materials,Grif14051 and PI502111,with average injury indexes of 16.67 and 21.91;6 resistance materials,such as PI196622,PI270907,PI390428,G11-5et al,the average injury index is between 26.33 and 42.41;32 medium resistant materials,such as PI648250,PI152146 and G11-6 et al,with the average injury index from 45.19 to60;34 susceptible materials such as PI576636,PI196635 and G11-21 et al,the averageinjury index is between 60.87 and 74.39;22 high susceptible materials,such as G5059,PI356004,G11-15,PI270786 and PI162857 et al,with the average injury index from 75.27 to 83.34.3.Twelve pairs of SSR markers were used to screen polymorphism of 77 American germplasm resources.The results showed that 103 polymorphic allele and the polymorphic rate of 20% to 100% with an average of 79.23% were obtained.From pod rot percentage,kernel rot percentage and injury indexes of three aspects respectively to identify the correlation analysis and stepwise multiple linear regression analysis we obtained 4 SSR markers to be significantly correlated with peanut pod rot resistance.The four markers were 3A8,GM1760,PM163 and 14H6,respectively.4.Forty eight pairs of InDel markers were also used to screen American germplasm resources and 15 pairs of polymorphic InDel markers were obtained.Pearson's correlation and stepwise multiple linear regression analysis were conducted based on InDel markers and injury indexes.The results showed that there were 2 InDel(004-InDel,020-InDel)markers to be significantly correlated with peanut pod rot resistance.This study not only confirmed the resistance of peanut germplasm from different sources but also provided excellent materials for genetic improvement of peanut disease resistance by rational utilization of germplasm,and also provided a standard for evaluation of resistance to peanut pod rot.The acquisition of molecular markers related to resistance to peanut pod rot provides an important reference for molecular assisted selection breeding and the excavation of disease-related genes. |
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