Genetic loci associated with freezing tolerance in a European rapeseed (Brassica napus L.) diversity panel identified by genome-wide association mapping

Authors: Chao, Wun; LI, XUEHUI - North Dakota State University; Horvath, David; Anderson, James

Submitted to: Plant Direct
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2022
Publication Date: 5/25/2022
Citation: Chao, W.S., Li, X., Horvath, D.P., Anderson, J.V. 2022. Genetic loci associated with freezing tolerance in a European rapeseed (Brassica napus L.) diversity panel identified by genome-wide association mapping. Plant Direct. 6(5):e405. https://doi.org/10.1002/pld3.405.
DOI: https://doi.org/10.1002/pld3.405

Interpretive Summary: Canola is an important oilseed crop contributing to the global demand for oil production. Although winter canola generally produces greater yields than spring canola, the range of winter canola is limited by its inability to withstand the winter conditions experienced in many regions of the northern U.S. Improving winter hardiness in canola requires knowledge of the many genes that control this trait. Using a genetics approach, we located 14 regions on eight chromosomes of a primarily northern European winter rapeseed population that are associated with freezing tolerance. The numerous genes within these regions could be potential resources for improving freezing tolerance. This knowledge should allow breeders to start integrating freezing tolerance traits into elite breeding lines of both winter- and spring-types of canola, and to increase canola production in the U.S.

Technical Abstract: Winter biotypes of rapeseed (Brassica napus L.) require a vernalization treatment to enter the reproductive phase and generally produce greater yields than spring rapeseed. To identify genetic loci associated with freezing tolerance in rapeseed, we first conducted genotyping-by-sequencing (GBS) on a diversity panel consisting of 222 rapeseed accessions originating primarily from Europe, which identified 69,554 high quality single-nucleotide polymorphisms (SNPs). The genotyped diversity panel was then phenotyped for freezing survival (visual damage and Fv/Fo and Fv/Fm) after two months of cold acclimation (5 °C) and a freezing treatment (-15 °C for 4 hr). The genotypic and phenotypic data for each accession in the rapeseed diversity panel was then used to conduct a genome-wide association study (GWAS). Model-based cluster analysis suggested that there were eight subgroups. GWAS results showed that fourteen significant markers were mapped to seven chromosomes for the phenotypes scored. Twenty-four candidate genes located within the mapped loci were identified as previously associated with lipid, photosynthesis, flowering, ubiquitination, and cytochrome P450 in rapeseed or other plant species.