| Chinese yam (Dioscorea polystachya Turcz.) is a kind of both medicine and food crops. The demand for the yam is rising year by year with more and more people put attention to healthy eating. It has been cultivated for thousands years in China. People of different areas often exchange their variety with each other, which lead the phenomenon of the yam in the market synonyms and homonym to be serious. So it is very important to identify and classify the yam accurately. and select the important and rare variety to improve the yam industry. The present study applied a combination of morphological markers and ISSR molecular markers to analyze the genetic diversity and genetic relationship of 46 yam germplasm from different areas of China. Finally core collection was constructed. The results are as follows.1. The Q cluster analysis by DPS analysis of 46 yam materials showed based on 13 morphological characters index:the genetic distance is 0.3199～10.4077. The 46 yam materials could be classified into two main groups when the threshold is 7.36, then the second class group can be classified into two groups. Based on the China Plants Database, the 46 yam materials can be divided into three groups:the Dioscorea alata, Dioscorea yunnanensis and general D. polystachya Turcz. and it is consistent with the results of clustering.2. Six subsets(XT70～XT10) were sampled by six sampling proportions(70%～ 10%), preferred sampling and UPGMA. Compare them with MD%,VD%,CR%,VR%, the results showed that the genetic diversity reached the greatest at the ratio of 30%, and the values with extreme genotypic was maintained. So the initial collection was well represented by the core collection of XT30.3. To compare the core collection, completely random and initial collection among different subsets in terms of mean, variance, range, coefficient and genetic diversity of variation, as well as the distribution map of core collection and completely random in the initial collection was drawn according to first two principal components, which amply demonstrated that the genetic diversity of initial collection could be well represented by core collection of XT30.4.17 primers were selected from 32 primers to PCR for 46 yam materials.253 clear strips were amplified, and 251 of them were polymorphic bands, the percentage of polymorphic bands was 99.21%,the fragment length is 100-2000bp. The average of Shannon information index (I), Nei’s genetic diversity (h), effective number of alleles (Ne) and number of alleles (Na) by POPGENE 32 analysis was 0.4435,0.2854. 1.4599 and 1.9921 respectively which indicated there was highly genetic diversity in these 46 yam resources, the genetic identity was 0.4861～1, and the genetic distance was 0～0.7212.which indicated there was highly genetic diversity in these 46 yam resources. The clustering result of analysis by NTsys2.10e software showed that the genetic similarity coefficient ranged 0.55～1.00. The 46 yam germplasm were divided into 3 groups when the Gs=0.66, and the third group can be divided into 4 groups. There were some special germplasms in each of the groups. The principal component plots showed the same result as the clustering analysis, and the relationship among 3 groups is more clearly.5. Six subsets(XT70～XT10) were sampled by Least Distance Stepwise Sampling in six sampling proportions(70%～10%). The change of genetic diversity index was not clear with the samples reduced in six samplings. There was high genetic diversity in subset of FZ30 and showed a good representative to the entire collection. FZ30 should be the core collection in ISSR marker.6. The result of principal coordinates analysis proved that the core collection (FZ30) could represent the initial collection in space.7. The FZ30 is more representative than XT30 both in phenotypic traits variation and in genetic diversity of ISSR. |
PDF Full Text Request