Exploration of the Brassica gene pools for early-flowering alleles for the improvement of earliness in Brassica napus canola without yield penalty

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Earliness of flowering and maturity are important traits for Canadian spring Brassica napus (AACC, 2n = 38) canola due to the short growing season in the Prairie Provinces. Breeding efforts in the last decades have improved the earliness in this crop to some extent; however, the level of earliness achieved so far does not exclude the predisposition of this crop to the danger of fall frost. To date, the earliness of the progenitor species B. rapa (AA, 2n = 20) has been exploited to improve earliness in B. napus; however, this is often achieved at the cost of seed yield. Therefore, further improvement of earliness and the identification of genomic regions that contribute to earliness without negatively affecting seed yield are needed. The long-term goal of my research program is to extend our knowledge on the allelic variation for flowering time genes present in different Brassica gene pools including B. oleracea (CC, 2n = 18) and to examine the effect of the early-flowering alleles on the physiology of the plant for the improvement of earliness in spring B. napus canola without yield penalty. The research to be carried out over the next five years is based on the hypothesis that flowering time alleles of the C genome of B. oleracea are different from the C genome flowering time alleles of B. napus and introgression of these alleles in B. napus will increase diversity for the flowering time alleles and ultimately improve the earliness in Canadian canola, and is guided by the following short-term objectives: (i) map the early-flowering alleles of B. oleracea var. alboglabra (Chinese kale), var. botrytis (cauliflower), var. capitata (cabbage) and var. italica (broccoli), which are being introgressed into B. napus canola, to understand the extent of diversity for early-flowering alleles that exists in the B. oleracea gene pool for the improvement of B. napus canola; (ii) understand the uniqueness of these alleles in the context of the flowering time alleles present in spring B. napus cultivars; (iii) understand the effect of these alleles on seed yield in B. napus; and (iv) characterize these alleles at the sequence level for the development of gene-based single nucleotide polymorphism (SNP) markers for use in breeding. The knowledge gained from this research can be applied for the development of high yielding early maturing canola cultivars for Canada; this will secure the crop from frost damage in early spring and fall, and from heat stress in mid-summer.