Genome Wide Association Mapping of Heat Stress Tolerant Traits in Rapeseed/Canola (Brassica napusL.)

Heat stress causes early abortion of flowers, pollen grain death and pollen sterility of rapeseed/canola. Seed yield contributing traits like pods per plant, pod length, seeds per pod, seed weight are suffered by heat. High temperature during flowering time significantly reduces the seed oil and seed protein content. This study is undertaken to identify heat stress tolerant gene through natural and artificial screening and molecular study. A total of 160 previously genotyped Brassica napus germplasm of spring type canola were naturally screened in the field. Screening of the same germplasm under artificial heat stress simulating condition in a walk-in plant growth chamber. A controlled experiment had set with the same germplasms without the heat stress treatment. The phenotypic data of the germplasms will be aligned with the SNP genotyping data to identify the genomic region controlling the heat tolerant gene(s) in the wide accessions of B. napus through a genome-wide association mapping. Variable pod abortion and pollen sterility were identified among the germplasms screened in the field. Under heat stress simulation condition in the growth chamber, high variation on pollen sterility, flower abortion, yellowing desiccated pod, pod abortion were observed compared with the control experiment. Several germplasm were identified tolerant to heat stress in growth chamber heat simulation conditions. The heat stress tolerant accessions will be used in breeding program to introgress the trait into elite breeding lines. Genome-wide association mapping will be conducted to find the genomic region controlling the trait.