Industrial rapeseed (Brassica napus L.) is a winter or spring annual crop that produces seed oil with a high level of erucic acid. The non-edible oil of industrial rape has the potential to be a sustainable source of hydrotreated renewable jet (HRJ) fuel, but a significant increase in the domestic production of industrial rapeseed oil is needed. In part, this could be accomplished through the large-scale introduction of industrial rapeseed as a rotation crop in the western U.S. non-irrigated wheat production system. Such introduction across the diverse environments that constitute the wheat belt, however, necessitates the development of high yielding, locally adapted industrial rapeseed varieties that are compatible with HRJ fuel conversion processes. In that light, we are constructing a translational genomics platform to support the genetic improvement of improved winter and spring type industrial rapeseed varieties.
In the first phase of the project, nearly 900 rapeseed lines that cover a wide geographic distribution were assessed for growth habit and scored with a high-density SNP genotyping platform. With this information, the ~900 lines were classified based on growth habit (winter or spring) and the genetic relationships assessed with a statistical clustering method, resulting in three distinct clusters. The three clusters were defined as winter and spring subpopulations, a naming convention based on the majority of lines with a specific growth habit in a given cluster. The two winter clusters could be further defined based on the predominant geographic origin of the included lines, “Asian” and “Western Europe.” This has helped improve our understanding of the genetic relationship among these lines and how genetic diversity is partitioned among them.
In the second phase, the ~900 lines are being evaluated in replicated field trials grown at Moscow, ID (Jack Brown, University of Idaho), Akron, CO (Merle Vigil, USDA-ARS), and Ames, IA (Jerry Hatfield, USDA-ARS), over three consecutive years. The spring lines are also being evaluated in replicated field trials in Maricopa, AZ (Erica Tassone and John Dyer, USDA-ARS). Our collaborators are scoring these lines for a number of agronomic and seed quality traits.
In the third phase, we will conduct a genome-wide association study (GWAS) separately in each of these diversity panels (winter and spring) to elucidate the genetic basis of important agronomic and quality traits. We will also employ linkage analysis in recombinant inbred line (RIL) populations to complement the GWAS results. Ultimately, the SNP markers associated with quantitative trait loci (QTL) will be used in a marker-assisted selection or genomic selection approach, depending on the genetic architecture of particular target traits, to accelerate the rate of genetic gain in industrial rapeseed breeding programs for enhanced production of HRJ fuel.
Funding: USDA-NIFA/DOE BRDI 2011-06476.