Study on Freezing Tolerance in Rapeseed/Canola (Brassica napus L.).

Freezing temperature/frosts can cause significant damage of plants by rupturing plant cells. Rapeseed/canola (Brassica napus) is susceptible to freezing temperature at early seedling stage. Different freezing tolerance studies on rapeseed/canola germplasm accessions have been conducted in the laboratory, controlled plant growth chamber, and field. The phenotyping data were aligned with genotyping data obtained from genotyping-by-sequencing. Genome-wide association study (GWAS) was conducted on each of the three experiments separately to identify potential markers/genes those were related to frost tolerance traits. The laboratory study identified 12 QTL located on 11 chromosomes A01, A02, A03, A04, A05, A07, A10, C01, C01_rand, Cnn_rand, and Unn_rand of Brassica napus. The controlled plant growth chamber study identified one QTL on chromosome A02, while the field study also identified one QTL on chromosome C04. All the GWAS studies identified several orthologs of the functional candidate genes involved in freezing/cold tolerance, abiotic stress tolerance, and transcription factors.