Genetic Diversity of Rapeseed Accessions from Different Geographic Locations Revealed by Expressed Sequence Tag‐Simple Sequence Repeat and Random Amplified Polymorphic DNA Markers

Abstract

ABSTRACTGenetic diversity information will be very valuable for future rapeseed (Brassica napus L.) improvement. The genetic diversity and relationships among 92 rapeseed accessions, including 44 from China, 22 from Europe, 16 from the United States, and 10 from Canada, were assessed by 60 random amplified polymorphic DNA (RAPD) and 22 expressed sequence tag (EST)‐simple sequence repeat (SSR) primers. In total, 618 RAPD and 117 EST‐SSR polymorphic fragments were detected. The average number of polymorphic fragments found by each RAPD primer was 10.3 ranging from 3 to 17 and that detected by each pair of EST‐SSR primer was 5.3 ranging from 4 to 7. The unweighted pair‐group method with arithmetic mean (UPGMA) cluster analysis revealed that these 92 accessions could be classified into three major clusters. Cluster I consisted of accessions mainly from China, which belong to the semi‐winter type. Cluster II contained accessions from Europe and the United States, which belong to the winter type. Cluster III was a semi‐winter and spring type mixture group, which contained accessions mainly from China and Canada. The principal component analysis and population structure analysis revealed similar results to the cluster analysis. Analysis of molecular variance result based on four geographic groups indicated that genetic variation was 8.24% among populations of geographic regions and 91.76% within geographic regions. Rapeseed accessions from the United Stated have the greatest genetic distance from accessions of other geographic origins, especially those from China. United States rapeseed could be important germplasm resources for enriching the genetic background of Chinese rapeseed and vice versa.