Genetic diversity and relationship analysis of the Brassica napus germplasm using simple sequence repeat (SSR) markers

Abstract

Oilseed rape (Brassica napus L.) is an important oilseed crop worldwide. The objective of this research was to study the genetic diversity and relationships of B. napus accessions using simple sequence repeat (SSR). A set of 217 genotypes was characterized using 37 SSR markers of mapping on the B. napus genome. The detected alleles were 2 to 11 at each of the 37 markers, with an average of 5.29 per marker. Unweighted pair group method with arithmetic mean (UPGMA) clustering enabled the identification of two general groups with increasing genetic diversity as follows: (1) group I was further divided into three groups (A, B and C), group A included 121 accessions, and consisted of the yellowseeded and black-seeded cultivars and breeding lines. The group B included 70 accessions and consisted mainly of the yellow-seeded cultivars and breeding lines, which were mostly cultivated in China. The group C included 10 accessions and consisted of the black-seeded cultivars and breeding lines with low levels of erucic acid. (2) Group II included 16 accessions consisted mainly of breeding lines and German cultivars, which were black-seeded lines with high levels of oleic acid (>80%) and low erucic acid and seed glucosinolate. The grouping of accessions by cluster analysis was generally consistent with known pedigrees, which included the grouping of lines derived both by backcrossing or self-pollination with their parents. The molecular genetic information gained enables also help breeders and geneticists to understand the structure of B. napus germplasm and to predict which combinations would produce the best off-spring which is potentially interesting with respect to increasing heterosis in oilseed rape hybrids.

Key words: Brassica napus L., genetic diversity, microsatellites, SSR markers.