Research On Genetic Diversity Of Passiflora Germplasm

Passion fruit belongs to Passiflora Linn, Passifloraceae. Most of them are herbaceous, although some representatives are shrubs or trees. There are about 16 genera in Passifloracea, with more than 600 species. In china, there are 19 species and 2 mutations including introduction and cultispecies, 9 species and 1 mutation lie in Xi Shuang Ban Na. At present, most of cultispecies are Passiflora edulis Sims, P. edulis Sim. f, flavica rpa Deg. and their hybrids. The study on the genetic diversity of passion fruit germplasms can benefit the collection, conservation, identifition, genetic enhancement and effective utilization of passion fruit. Molecular mark can detect the genetic diversity at DNA level,and it is a powerful tool to study genetic diversity in plant. ISSR marker has been popularized for simplicity, rapidity, good repetition, high polymorphism and current primer. In this study, the genetic diversity in 33 genotypes of 62 accessions was assessed using ISSR markers and morphological descripors, with cluster analysis, principal coordinates analysis and factor analysis. The main results were as follows:1. The 62 accessions were classified at least as 33 different genotypes by primary with 6 good polymorphous primers. Repeated experiment of accessions with same genotypes were avoided with less work.2. 14 primers generated 228 bands with size from 200bp-3000bp, of which 227 bands(99.56%) were polymorphic. Cluster analysis via NTSYS-PC2.10a software showed that all accessions were divided into 5 groups while the Dice coefficient was 0.73. The first group only had G8, the second group concluded G12and G30, the third group concluded G29 and G31, the fouth group include G32 and G33, the last group concluded the rest of 26 genotypes. The result of principal coordinates analysis was similar to cluster analysis, but the former was more intuitionistic than the latter.3. Basic statistic analysis was performed for 24 morphological characters of 29 passion fruit accessions. The result showed every character lied in different degree of discrepancy between accessions, and the average coefficient of variation was 20.69%, Variation coefficient of TSS-Acid ratio was the biggest(61.41%), and next came the organic acid content,esters in flesh and flesh color, Variation coefficient of fruit width was the smallest(6.67%). Cluster analysis showed 29 accessions were divided into 3 kinds, when euclidean distance was 7.874. The first kind concluded G31 and G32, the second kind concluded G1,G23 and G33, the third kind concluded the rest of 24 genotypes.Factor Analysis was carrtied out for 12 fruit quantitative characters and the results indicated that 12 fruit characters of the varieties might be simplified to 5 main independent character groups controlled by 5 grain factors.4. According to the results of two markers,genetic diversity of passion fuit germplasms in Xi Shuang Ban Na was extensive, but most of cultispecies had higher genetic comparability.