Morphological Classification, SRAP Molecuar Marker Analysis And DNA Fingerprinting Primary Construction Of Yam Germplasm Resources

Yams are twining and herbaceous perennials belonging to Diosecrea genus of Dioscoreaceaefamily, containing many nourishing ingredients and biological active compositions and possessing highedible and medical value. For a long period of domestication and cultivation yam species developed aseries of cultivars. But it lacks name standard in the course of yam cultivars introduction and extension,which results in names or species confusion. Therefore, collecting, classifying and correctlydistinguishing are important for the development and utilization of yam germplasm resources. In thispaper, morphology diversity of 94 yam germplasm resources from 13 provinces of China wereinvestigated, and a classification system according to morphological traits of yams was made. Geneticdiversity of yam resources was systematically analyzed by means of molecular markers SRAP.Moreover, DNA Fingerprinting of yam resources was preliminarily constructed. The major results are asfollows:1. 25 overground and underground agronomical traits were studied using system cluster analysismethod, and the dendrogram of clustering was constructed. As the chi-square distance was 3.17, the 94yam resources were divided into three populations: Groupâ… , Groupâ…¡and Groupâ…¢, containing 70,19 and 5 resources respectively . Groupâ… fourthly was divided into two subgroup when the chi-squaredistance was 2.38. Moreover, the first subgroup also had two branch. Groupâ…¡had two subgroup asthe chi-square distance was 2.12. Both group and subgroup had different features significantly.According to the morphological characters, the 94 yam resources could be divided into four types:Dioscorea polystachya, Dioscorea persimilis, Dioscorea fordii and Dioscorea alata. Themorphology of leave and underground tuber were significant different from each other. In the result ofsystem cluster analysis, for Group I, the first branch of Subgroupâ… was Dioscorea polystachya , thesecond was Dioscorea persimilis, and the second subgroup was Dioscorea fordii. Group II and IIIbelong to Dioscorea alata. According to the morphological investigation and cluster analysis on yamresources, a classification system was made with the flesh color as the type classification index andtuber shape as the cultivar group classification index.2. 30 primers screened out of 49 primers were adopted to analyze the polymorphism in the SRAPprofiles. 754 SRAP bands were acquired, in which 616 bands were polymorphic at a percentage of81.7%. The results of SHAN cluster analysis using NTSY2.10 showed that when the genetic similaritycoefficient was 0.822, the 94 resources could be classified into 5 types: Typeâ… ,II, III, IV and Vcontained 20, 43 , 7, 3 and 21 resources, respectively. Typeâ… ,â…¡,â…¢andâ…¤were Dioscoreapolystachya, Dioscorea persimilis , Dioscorea fordii and Dioscorea alata, respectively, whichidentifying morphological classified results. The 3 yam resources in Typeâ…£were clustered to anunique group because of their bulbils. Using the amplification results of SRAP-PCR, Principalcomponent analysis was done by NTSYS 2.10, and genetic diversity parameters were estimated by POPGENE. Principal component analysis indicated that the first two PCAs accounted for 88.34%(82.10% and 6.24%)of the total variation observed. In PCA map, Dioscorea alata and Dioscoreapersimilis could be distinguished clearly, but Dioscorea polystachya and Dioscorea fordii could not,which indicated the genetic diversity between Dioscorea alata and Dioscorea persimilis was higher thanthat of the other two. According to the index value of five genetic diversity in SHAN cluster analysis,the rate of polymorphism sites, alleles, effective alleles, genetic diversity and diversity index wereanalyzed. Results showed that the level order of genetic diversity in five types wasâ… >â…¤>â…¢>â…¡>â…£. Ahigh level of genetic differentiation among yams types was detected based on Nei's diversity analysis(51.88%). The rich germplasm resources and high level of genetic differentiation played an importantrole of the new varieties breeding on yams.3. Using SRAP-PCR amplified bands, the Excel document with the fingerprints database ofanalyzed yam germplasm materials were built. According to the uniqueness principle of fingerprintsbands, this study adopted a software analyzing data of DNA fingerprints and depicted the fingerprintbands of analyzed materials. It screened 12 polymorphic primers as M6E6,M6E8,M6E9,M8E8,M9E6,M9E11,M10E10,M11E6,M11E11,M11E13,M12E11and M12E12 from 30 primers withhigh polymorphism, which could be regarded as molecular identification of fingerprints bands on yamresources, and a DNA fingerprint map with 86 resources of yam was primary constructed. Thisresearch primarily probes and attempts to depict the fingerprints bands of yam germplasm resources forthe first time.