Studies On Genetic Diversity Of Ornamental Pepper Germplasm Resources

Ornamental pepper is an important horticultural plant and have red, yellow, orange, purple, white et al. various fruit colour. The study on the genetic diversity of ornamental pepper can benefit the conservation, classification, identification, genetic enhancement and effective utilization of the ornamental pepper germplasm resources. Molecular marker, which can detect the genetic diversity at DNA level, is a powerful tool to study genetic diversity. RAPD markers have been popularized for their simplicity, rapidity and non-specialty among different genera. In this study, the genetic diversity in 67 ornamental pepper accessions from different countries or regions was assessed using morphological descriptors and RAPD markers, and the genetic relationship among the accessions was revealed by hierarchical cluster analysis, principal components analysis and correspondence analysis at various level. The main results were as follows:A total of 40 morphological descriptors were measured, 23 qualitative and 17 quantitative, for assessing genetic diversity of 67 ornamental pepper germplasm. The average coefficient of variation was 47.5%. They ranged from 22.27% in leaf colour to 101.28% in corolla colour based on the 23 qualitative descriptors and from 8.94% in days to flowering to 187.61% in depth of pedicel grooves based on the 17 quantitative descriptors.The average Shannon's Information index among the accessions was 0.80 based on the data of 40 morphological descriptors. They varied from 0.27 to 4.06.The 67 ornamental pepper germplasm were clustered into 5 groups based on the morphological data. The results of principal components analysis showed accumulative variance contribution of the first three principal components was 85.74%. The variance contribution of the first principal component was 63.06%. It mainly expressed that fruit weight are the decisive factors affecting Ornamental pepper germplasm classification according to morphological characters. In correspondence analysis, the 67 ornamental pepper germplasm were separated into 3 groups and the 40 morphological descriptors were divided into 3 groups. The first group morphological descriptors were corresponded to the first and second groups ornamental pepper germplasm. The second group morphological descriptors were corresponded to the third group ornamental pepper germplasm.A total of 100 10-mer random primers was used in this study. Among them, 19 primers produced 134 scorable and repeatable RAPD bands, of which 113 bands (84.33%) were polymorphic across 67 ornamental pepper accessions. The gene diversity and Shannon's Information index of RAPD loci was 0.3073 and 0.4682. 67 ornamentalpepper germplasm were clustered into 4 groups based on the RAPD data by the method of hierarchical cluster analysis. The accumulative variance contribution of the first three principal components was 35.7%. The first principal component encompassed only 20.22% of the total variation.All the results above confirmed that the level of polymorphism was high in the 67 ornamental pepper germplasm. The 6 germplasm from oversea and the others had larger genetic distance. The genetic distance of bell type ornamental pepper germplasm were smaller. The cluster redpepper type germplasm were clustered to one group.