| Pepper(Capsicum spp.)is one of the important vegetables and peppery spice,belongs to the Solanaceae,genus Capsicum.Its fruit has a special spicy taste.In China,most of the pepper cultivars are C.annuum L,the genetic back ground of pepper germplasm resources is relatively narrow for the pressure of long-term artificial selection and the wide spread of pepper hybrid varieties.Therefore,it is of great significance to collect and preserve pepper germplasm resources as well as study their diversity and construct the core collection.In this study,we studies genetic diversity of 512 pepper germplasm and construction of primary core germplasm based on SRAP marker,and then construct core germplasm of re-compression primary core collection with SSR markers.The main contents and results are as follows:(1)Genetic diversity analysis of pepper germplasm based on SRAP.21 pairs of polymorphism primers screened from 266 SRAP primer,and 685 bands are obtained by all those primers amplifying in 512 pepper materials,32.62 bands and 23.10 polymorphic bands were detected by each pair of primers,with the polymorphic rate of 69.9%.The genetic diversity analysis showed that the effective alleles number,gene diversity and Shannon Index of diversity of A-2 groups were less than group A-1 and A-3.The clustering analysis results showed that the genetic similarity coefficient of 512 pepper germplasms was 0.543~0.997,the average 0.841,at similarity genetic coefficient level of 0.640 where all the tested materials able to distinguish 3 major groups,at similarity genetic coefficient level of 0.836 where all the tested materials in C.annuum L could be divided into 5 groups.(2)Establishment of the primary core collection of pepper germplasm resources based on SRAP Makers.According to the results of SRAP molecular marker,stepwise clustering method was used to screening the primary core collection,constructs 288 samples as primary core collection that hold 56.25% samples of initial collection.The validity test for primary core collection,the results showed that the difference of the effective allele number was 1.2262,Nei’s genetic diversity index was 0.1407 and Shannon’s information index 0.2255,which was not significant with initial collection.Those results indicated that primary core collection could represent initial collection effectively.(3)Genetic diversity analysis of primary core germplasm of pepper germplasm resources based on SSR.There were 362 polymorphic fragments using 65 pairs of polymorphic primers screened from 153 SSR primers,and 5.57 allelic loci were detected by each pair of primers,with the polymorphic rate of 100%.The genetic diversity analysis of pepper populations based on SSR marker showed that the gene diversity was 0.1287 andShannon Index of diversity was 0.2005 of B-2 groups were less than group B-1 and B-3.The results indicated that the genetic variation in C.annuum is less than that among cultivated Capsicum species.The clustering analysis results showed that the genetic similarity coefficient of 288 pepper germplasms were 0.008~0.955,with the average value of 0.445,and at similarity genetic coefficient level of 0.236 where all the tested materials were able to distinguish 3 major groups,at similarity genetic coefficient level of 0.418 where all the tested materials in C.annuum L could be divided into 7 groups.(4)Establishment of the core collection of pepper germplasm resources based on SSR makers.According to the results of SSR molecular marker,stepwise clustering method was used to screening the core collection,200 samples were chosen as primary core collection that retained 39.05% samples of initial collection.The validity test for core collection,the results showed that except for observed number of alleles,other indexes were not significantly different with primary core collection.Those results showed that primary core collection could represent primary collection effectively. |
