| China is one of the original centers of genus Malus. It has abundant apple gemplasm resources,which plays an important role in the research of apple origination,evolution,and genetic diversity. Because of the high heterozygosity of genotype, many problems correlative to taxonomy and classification are under solution. SSRs are very suitable for the research on genetic diversity and phylogenetic relationship since they are more reliable, co-dominant in heritance, large number of alleles per locus, and abundance in genomes.The phylogenetic relationship and genetic diversity among 59 apple accessions belong to 19 species have been analyzed by using SSRs including 17 cultivars, 10 wild apple accessions in Xinjiang Antonomous Region,13 regional cultivars and 19 wild apple accessions or their varieties. Main results of the present study are as follows:1. SSRs are very suitable for the research on genetic diversity and phylogenetic relationship since they are more reliable, co-dominant in heritance, large number of alleles per locus, and abundance in genomes. 12 pairs of SSR primers selected from 20 pairs amplified 176 alleles, with an average of 14.7 alleles per locus. Locus heterozygosity was 0.4039 to 0.7412, and the genetic diversity index was 0.6156.2. SSRs can identify varieties effectively and accurately based upon differential fingerprint of different species or varieties at different loci. SSR fingerprints of 59 apple accessions were constructed. Among the 12 pairs of primers, three pairs (CH02a04,CH02g04 and CH01f03b) could distinguish all of the apple accessions, and the afficiency of CH02a04 and CH04h02 is 74.6% and 71.2% respectively. And 17 cultivars, 10 wild apple accessions in Xinjiang Antonomous Region, 13 regional cultivars and 19 wild apple accessions or their varieties could be distinguished by using 2 pairs, 1 pair, 1 pair and 2 pairs respectively.3. The dendrogran of 59 apple accessions was constructed. Based on the SSR results, the similarity coefficient is between 0.7226～0.9935 with an average of 0.8070. The 59 apple accessions could be classified into three groups at 0.803.Clusterâ… contains all the wild apple accessions or their varieties, clusteâ…¡contains regional cultivars and all of the wild apple accessions in Xinjiang Antonomous Region,clusterâ…¢contains all the cultivars belonging to European and Asian groups together with two regional varieties (Laoshannaizi and Niumamahaitang). Maybe Laoshannaizi and Niumamahaitang are close to cultivars.4. The comparision of SSR results with previous researches on origin,genetic diversity of genus Malus was done. The result of the research is accordant to the new classification system of genus Malus,and supply molecular evidences for the adscription of Zhumeihaitang (M.zumi (Mats.) Rehd.), Bianyehaitang (M. toringoides (Rehd.)Hughes.),etc.. |
