Genetic diversity in mulberry (Morus spp.) revealed by isozyme markers

摘要

Nine isozyme patterns were studied to deduce the level of genetic diversity and inter-relationships among 14 species of mulberry (Morus spp. L) used in breeding programmes. beta-Esterase (EST), peroxidase (PoX), diaphorase (DIA), and polyphenol oxidase (PPO) produced 12 isozyme loci and a total of 22 alleles. The percentage of polymorphic loci and the average number of alleles per locus ranged from 50 - 75% and 1.336 - 1.667 respectively. Among 80 wild accessions of two wild and two domesticated species of Morus, 22 accessions of M. alba exhibited a higher number of polymorphic loci (75%), a higher polymorphic index (0.398), average number of alleles per locus (1.457), and expected heterozygosity (0.339) compared to the three other Morus species under study. Evidence for a higher rate of gene flow was found between populations of M. alba and M. indica compared to that between the other three species sampled. Phylogenetic clustering of the 80 wild mulberry accessions indicated three major groups. Accessions of the domesticated species grouped into one cluster, while accessions of the wild species grouped into one major and one minor cluster. Among all the isozyme loci, EST-2 was present only in polyploid species. The resolving power of isozymes was less than that of molecular markers, hence molecular markers should be used for phylogenetic studies in mulberry.