Genetic diversity in Chinese and exotic Brassica rapa L. accessions revealed by SSR and SRAP markers

Abstract

The genetic diversity and relationship was studied in a collection of 65 Brassica accessions, which included 54 B. rapa and 11 of five other Brassica species used as references. These 54 B. rapa accessions included 42 Chinese accessions and 12 exotic accessions. All accessions were analyzed by using 36 simple sequence repeats (SSR) and 43 sequence-related amplified polymorphism (SRAP) primers, and 401 polymorphic fragments were detected by SSR and SRAP markers. The average number of polymorphic fragments detected by SRAP markers was 6.23 ranging from 2 to 11 and that revealed by SSR was 3.69 ranging from 2 to 7. The unweighted pair-group method with arithmetic mean cluster analysis indicated that all accessions could be divided into five major clusters except three accessions as outliers. The exotic B. rapa accessions appeared in Cluster I except one yellow sarson accession from India, Chinese B. rapa revealed in Cluster II, and 11 accessions of other Brassica expressed them Cluster III, Cluster IV, and Cluster V. The results of principal component analysis and population structure analysis were in accordance with the cluster analysis. Molecular variance analysis revealed that the genetic variation was 26.10% among populations and 73.90% within Brassica species, which indicated existence of considerable genetic variation among exotic and Chinese B. rapa species, and exotic B. rapa can be used for broadening the genetic background of Chinese B. napus, and vice versa.