Abstract:

【Objective】 It is very important to make studies on the genetic diversity of wild, semi-wild and cultivated azuki beans for further detecting the origin, evolution and diffusion of azuki bean and effectively utilizing these germplasms and serving for azuki bean improvement. 【Method】 Eleven higher polymorphic SSR primers screened from 69 SSR primer pairs of azuki bean and black gram were used in amplification of 558 wild, semi-wild and cultivated azuki bean accessions from China, Japan, South Korea, Bhutan and Burma. The analysis of genetic diversity and trait association was done.【Result】 Eighty-six polymorphic bands were generated. An average of 7.28 polymorphic bands were detected from 1 pair SSR primers. The number of alleles changed from 6 to 10. There were specific bands were observed in wild, semi-wild and cultivated azuki beans. Specific bands of cultivated azuki bean were predominantly produced by Chinese cultivars and landraces. Specific bands of wild azuki bean were detected in accessions from China, Bhutan and South Japan. The order of genetic dispersion was wild＞semi-wild＞cultivated azuki beans. Semi-wild accessions has closer genetic relationship with wild azuki bean. The 558 accessions were divided into five main groups by cluster analysis according to genetic distance. The result of cluster appeared that the genetic types of azuki beans have obviously associated with different geographical regions. Japanese cultivated azuki beans have closer genetic relationship with wild and semi-wild accessions from Japan and South Korea. Wild accessions from Southwest China are closely related to wild accessions from Southeast Asia and landraces of Jiangsu Province. Trait association analysis showed that black gram BG111 marker located on linkage group 7 of azuki bean explained 49%, 44%, 31%, and 18% traits of number of nods on main stem, diameter of stem, top stem twining and branching numbers in wild and weedy types. BG48 of linkage group 1 and BG20 markers of linkage group 5 from black gram and azuki bean AZ24 marker of linkage group 9 accounted for 9%, 7%, 5%, and 6% traits of maturing days, plant height and seed number per pod, number of nods on main stem in cultivated azuki bean respectively.【Conclusion】 A higher genetic variation was detected in wild types than in cultivated accessions. Chinese cultivated azuki bean is originated from China and has the most diversely genetic variation. Number of nods, diameter of stem, top stem twining and branching numbers in wild and semi-wild types are related with black gram BG111 marker. Maturing days, plant height and the number of seeds per pod, number of nods on main stem are associated with black gram BG48 and BG20, azuki bean AZ24 markers in cultivated azuli bean, respectively.

Key words: azuki bean (Vigna angularisi), different type, SSR, genetic diversity, trait association analysis