Studies On Genetic Diversity And Relative Of Melon Germplasm Resource

Melon (Cucumis melo L.; 2n=2x=24) is an important horticulture crop across wide areas of the world.It is a estremely diverse depending on the fruit variation and vegetative morphology. Great morphologicai vafion exists in fruit characters such as size, shape, color and taste of melon fruit, and melon is considered as the most variable species in the genus Cucumis. It is urgently needed to evaluate of germplasm and its distribution, understand the genetic relationship of germplasm and identify some new genes for effective melon germplasm colletion and management and for melon breeding.In this study ,the genetic diversity in 76 melon accessions from different region of china was assessed using 37 morphological descriptors.The morphological descritors include 26 qualitative and 11 quantitative.The average coefficient of variation was 37.9% They ranged from 21.25% in length of seed to 76.34% in covered veins on fruit rind and the color of covered veins based on 25 qualitative descriptors and from 7.16% in number of days after sowing to harvesting to 41.94% in flesh thickness based on the 11 quantitiative descriptors.The average Shnnon's information index among the accessions was 1.24 based on the data of 37 morphological descripors. They rang from0.28 to 2.06.The 76 melon germplasm were clustered into 3 major groups based on the morphological data. One muskmelo was far from other accessions.it's taste is acid. 15 netted muskmelon accession from xinjiang autonomy sanjak and two netted muskmelon accession from Japan were got together. Then the third group was consisted of cucumis melo sp.concomon and several variation of muskmelon. It was apparent that there was some association between morphological similarity and geographical distribution.In the study, the genetic diversity in melon accessions from different countries or regions was assessed by random amplified DNAs(RAPDs) .The results showed:20 primers produceing qualified fragments were screened from 100 random primers, RAPD markers by 20 informative primers were used to determine the frequence of DNA polymorphism in melon germplasms. A total of 108 bands were detected among 76 melon accessions from different countries and regions. The genetic diversity is rich. Of them 81.20% bands were polymorphic.all accessions wern group into 7 major gruops .One netted muskmelon was group from other accession.All muskemelon from xinjiang autonomy sanjak were got together with other muskmelon variation.Two netted muskmeon from Japan were got together with two cucumis melo sp.concomon and two casaba muskmelon.Cucumis melo sp.conomon and some muskmelon were togethered in seventh group. The clusters were greatly indentified with the origins.The results were consistent with morphological classificationAll the results showed, the study on cluster analysis of melon will deepen the comprehension about thegenetic diversity of melon accessions and the genetic distance of different groups. The difference within cultivars is obvious.The genetic diversity of melon accessions is rich, which will offer some instructive help to melon breeding.