Resistant Genetic Analysis And Screening ISSR Molecular Marker Of Cucumber Mosaic Virus (CMV) In Pepper

Cucumber mosaic virus (CMV) is one of the most widespread plant viruses,which has been intensively studied ,caused serious loss in the world.At present, there are few reports about the resistance-inheritance and markers linked to resistant gene of CMV in pepper.This papper analyzes pepper genetic resistance to CMV,and screens ISSR markers linked to resistant gene by using Vc16a,SS79 and SS69.The results will provide theoretical basis about genetics and molecular biology for resistance breeding.1. Genetic analysis of resistance to CMV in pepper: Disease status in F2 generation was analyzed to reveal genetic resistance at seedling and maturation stages by using segregating generation method of plant quantitative traits.The results indicate that the resistant inheritance controlled by two pairs of major genes in seedling and maturation stages, but there are some differences among the effects of major genes. In seedling stage,the genetic model of 05CM-8,05CM-9and 05CM-11 are all Model B-1, which is additive-dominant-epistatic effects.05CM-10 fits B-2,which is additive-dominant effects. The heritabilities of the major genes of 05CM-8 and 05CM-10 both are 100%, 05CM-9 and 05CM-11 are 93.97% and 99.33%, respectively. In maturation stage,pepper resistance to CMV is also controlled by two pairs of major genes, but there is some differences to that of seedling stage.The genetic models of 05CM-8 and 05CM-10 are model B-2,and 05CM-9 and 05CM-11 are B-1. The major genes'heritabilities are: 05CM-8 100%,05CM-10 95.04%, 05CM-9 62.91%,and 05CM-11 61.32%.2.Optimization of ISSR reaction system for pepper: In this experiment, orthogonal design with three levels and four factors (Taq DNA polymerase, dNTPs, primer and Mg²⁺) was used to optimize the pepper ISSR-PCR reaction system. The results showed that a best amplification of ISSR was obtained with the reaction system containing 1×PCR buffer, 1.5mmol/L Mg2+,50ng template DNA of pepper, 1.5U Taq polymerase, 200μmol/L dNTPs, 0.6μmol/L primer in the total volume of 20μL.3.Screening of ISSR marker: A resistant group and a sensitive group were divided with'BSA'method to search for the markers with resistance linked to CMV. 40 primers are used to select resistant markers between Vc16a and SS69.Polymorphic products were amplified between the resistant group and the sensitive group by using I-3, I-10, I-13 and I-34 of the 40 primers. Verification and linkage analysis in the F2 generation used the four primers, which indicated that I-13 linked to I-34,and genetic distance was 16.3cM.The polymorphic band was 1100bp and named I-131100;I-34 linked to CMV resistance-site in pepper,and genetic distance was 27.3cM.The polymorphic band was 450bp and named I-34450.