Resynthesis of Brassica napus L. for self‐incompatibility: self‐incompatibility reaction, inheritance and breeding potential

Abstract

Self‐incompatibility (SI) in Brassica has been considered as a pollination control mechanism for commercial hybrid seed production, and so far has been extensively used in vegetable types of Brassicas. Oilseed rape Brassica napus (AACC) is naturally self‐compatible in contrast to its parental species that are generally self‐incompatible. Introduction of S‐alleles from its parental species into oilseed rape is therefore needed to use this pollination control mechanism in commercial hybrid seed production. Self‐incompatible lines of B. napus, carrying SI alleles in both A and C genomes, were resynthesized from self‐incompatible B. oleracea var. italica (CC) cv.‘Green Duke’ and self‐incompatible B. rapa ssp. oleifera (AA) cv. ‘Horizon’, ‘Colt’ and ‘AC Parkland’. All resynthesized B. napus lines exhibited strong dominant SI phenotype. Reciprocal cross‐compatibility was found between some of these self‐incompatible lines. The inheritance of S‐alleles in these resynthesized B. napus was digenic confirming that each of the parental genomes contributed one S‐locus in the resynthesized B. napus lines. However, the presence of two S‐loci in the two genomes was found not to be essential for imparting a strong SI phenotype. Possible use of these dominant self‐incompatible resynthesized B. napus lines in hybrid breeding is discussed.