HO-CR and HOLL-CR: new forms of winter oilseed rape (Brassica napus L.) with altered fatty acid composition and resistance to selected pathotypes of Plasmodiophora brassicae (clubroot).

The priority in oilseed rape (Brassica napus L.) research and breeding programs worldwide is to combine different features to develop cultivars tailored to specific applications of this crop. In this study, forms with a modified fatty acid composition of seed oil were successfully combined with a source of resistance to Plasmodiophora brassicae Wor., a harmful protist-causing clubroot. Three HO-type recombinants in F-F generations with oleic acid content of 80.2-82.1% and one HOLL-type F inbred mutant recombinant (HOmut × LLmut), with a high oleic acid content (80.9%) and reduced linolenic acid content (2.3%), were crossed with the cultivar Tosca, resistant to several pathotypes of P. brassicae. The work involved genotyping with the use of DNA markers specific for allelic variants of desaturase genes responsible for the synthesis of oleic and linolenic fatty acids, CAPS (FAD2 desaturase, C18:1), and SNaPshot (FAD3 desaturase, C18:3), respectively. Of 350 progenies in the F generation, 192 (55%) were selected for further studies. Among them, 80 HO (≥ 72%) lines were identified, 10 of which showed resistance to at least one up to four P. brassicae pathotypes. Thirty lines in the selected progeny contained high oleic acid and less than 5% linolenic acid; eight of them belonged to the HOLL type conferring resistance to at least one pathotype. Two HO lines and two HOLL lines were resistant to four pathotypes. The resulting HO-CR and HOLL-CR inbred lines with altered seed oil fatty acid composition and resistance to P. brassicae represent unique oilseed rape material with the desired combination of valuable traits.