Pedigrees and genetic base of flax cultivars registered in Canada

Flax is an important oilseed crop with industrial, animal, and human nutrition uses. Breeding programs for linseed and fibre flax were initiated in Canada in the early 1900s. A total of 82 flax cultivars have been registered in Canada since 1910, including 24 cultivars introduced from foreign countries and 58 cultivars developed by Canadian breeders. This study collated pedigree data of Canadian flax cultivars and quantified their genetic base via pedigree analysis and coefficient of parentage (CP). A fairly high mean CP of 0.14 was observed between all registered cultivars; this value was even higher (0.23) when only the 46 cultivars released from 1981-2015 were considered. The registered cultivars traced back to 46 ancestors; 72% originated from foreign countries and contributed 83% of the genetic base of all cultivars, illustrating the dominant role played by foreign germplasm in the genetic improvement of Canadian flax. The top 11 ancestors contributed 70%-93% of the genetic base of modern flax cultivars released in the last three decades and formed the core gene pool of Canadian flax cultivars. The genetic base of Canadian cultivars is relatively narrow, although it has gradually expanded, especially in the last two decades. Broadening the genetic base through the introduction of new exotic germplasm is needed to invigorate the gene pool of Canadian flax breeding programs.