Genetic structure of synthetic Brassica napus L. Populations

Abstract

The crop species Brassica napus L. has significant economic importance around the world. However, the complex evolutionary history and vast geographical distribution of oilseed rape has contributed vastly to genetic population structure investigations. Constant breeding efforts, for use for oilseed rape as food for human consumption, and fodder for livestock, have generated new phenotypic diversity. In this study, we used crosses among very diverse morphotypes as Brassica oleracea (turnip rape), conv. capitata var. medullosa (Cavalier rouge), conv. capitata var. sabauda (Savoy 'Wirsing'), conv. botrytis var. alboglabra (broccoli); Brassica rapa (turnip), var. trilocularis (yellow sarson), var. chinensis (bok choy); Brassica cretica; Brassica montana. Until now, genetic studies had insufficient genotypes to determine the relationship of oilseed morphotypes and their genetic population structure. We used 18,272 single nucleotide polymorphism markers in a synthetic nested association mapping diverse panel of 200 B. napus accessions that included crosses of five very diverse parental lines and a common elite accession. Results on population genetic structure and phylogenetic analyses revealed, as expected, five subpopulations that were largely reflective of phenotypes. The results of this study have provided improved resolution to the genetic and phylogenetic relationships of a synthetic panel within the Brassicas species. Understanding genetic diversity available is key to the future genetic study and constant improvement of this important agronomical crop species.