Analysis Of Genetic Diversity And Relationship Of Cucurbita By AFLP

Cucurbita is cultivated widely all over the world. There are Cucurbita distributions throughout our whole country, and its germplasm resources are plentiful in China. Cucurbita has abundant nutritional ingredients and high officinal value. So more and more researchers paid attention to the exploitation and utilization of cucurbita. However, for a long time the attention paid on conservation, exploitation and utilization of cucurbita germplasm resources was far from enough. The phenomenon of mixed varieties is serious. So it is very important to collect, evaluate and utilize the cucurbita germplasm. 88 representative cucurbita accessions were collected from different countries or regions in order to study on their genetic diversity and relationship. The purpose of this experiment is to understand their diversity distributions, genetic relationships and classification statuses and identify some new genes from molecular level, which are beneficial to the collection, conservation, exploitation and utilization of cucurbita germplasm. The main results were as follows:In this study, AFLP technique was applied to analyze the genetic diversity and relationships of 88 cucurbita germplasm resources.10 pairs of E+2/M+3 primer combinations were screened out from 64 pairs. A total of 515 scorable bands were amplified, of which 202(39.22%) showed polymorphic. The highest polymorphic prime pair was E-TT/M-CAC, and its polymorphic rate was 51.06%. On the contrary, E-AT/M-CAT primer pair generated the lowest polymorphic bands, which polymorphic percentage was 13.46%. The results indicated that primer selection was important for overall understanding of genetic diversity.UPGMA clustering method was carried out by two cluster analysis softwares—NTSYS package and MEGA2.1 for the cluster analysis of AFLP data and the results of the two cluster analysis softwares were just the same. 88 accessions could be taxonomied into four groups which were Cucurbita moschata D. cluster, Cucurbita pepo L. cluster, Cucurbita maxima cluster and Cucurbita. ficifolia cluster at 0.55 similarity coefficient for NTSYS package and 0.20 similarity coefficient for MEGA2.1, respectively. Among the four groups, the relationship between Cucurbita ficifolia and Cucurbita pepo L. was closer, Cucurbita moschata D. was next and Cucurbita maxima D. was farthest. Among three main cultivated varieties, the relationship between Cucurbita pepo L. and Cucurbita moschata D. was closer than that between Cucurbita pepo L. and Cucurbita maxima D.Cucurbita moschata D. cluster included plentiful germplasm. Their morphological differences of leaf shapes, fruit shapes and colors were also very obvious. The genetic diversity of Cucurbita moschata D. was related to the long history, wide field and various entironment in China. It proved that cucurbita had broader genetic background in China from DNA level.