Physiological race and genetic diversity of Phytophthora capsici in Chongqing
In this study,the mating types,physiological race composition,and genetic structures of 66 Phyto-phthora capsici isolates,collected from Chongqing during 2019-2020,were revealed by antagonistic culture,root-irrigation inoculation of differential hosts,and simple sequence repeats(SSR)marker-based analysis.The results showed that there were 53 P.capsici isolates of A2 mating type and 13 isolates of A1 mating type;11 iso-lates of race 1,28 isolates of race 2,1 isolate of race 3,and 2 isolates of race 6.Genetic variation analysis of the P.capsici population,which consists of 11 different geographical sub-populations,was carried out by using six common SSR markers,and 59 different genotypes were obtained in total,with effective alleles of 1.786-2.881,expected heterozygosity of 0.352-0.577,Shannon-Wiener index of 1.242-2.079,and percentage for polymorphic markers of 83.33％-100％,and high levels of gene exchange occurring within subgroups(Nm=0.133-7.680)were indicated by medium population differentiation(FST=0.113).It was concluded that the degree of genetic variation of P.capsici populations in different regions of Chongqing was different,while the whole population had a surplus of heterozygotes,indicating a rich genetic diversity.The mating type proportion,fixation index,Hardy-Weinberg balance and linkage disequilibrium analysis for each geographical population showed that asexu-al and sexual reproduction may co-exist in P.capsici populations of Chongqing.Analysis of molecular variance(AMOVA)further showed that genetic variation mainly occurred within populations.Discriminant analysis of principal components(DAPC)showed that there were obvious differences and group division among P.capsici isolates from Chongqing,which could be divided into two groups.Structural analysis showed that P.capsici in Chongqing may come from two different ancestral groups.The results lay a basis for the control of Phytophthora blight of pepper plants.
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万方数据
