Creating favourable morphological and yield variations for rapeseed by interspecific crosses between Brassica rapa and Brassica oleracea

Brassica napus is a most important oilseed grown worldwide with a limited genetic background, due to the short history of speciation, domestication and cultivation. Tocreate novel germplasm for rapeseed breeding, we made interspecific crosses followed with chromosome doubling between B.rapa and B.oleracea to generate novel B.napus with favourable agronomic traits. The resynthesized (S0) hybrids were confirmed by SSR and cytogenetic analysis, and the fertility was increased from 32.7% in S0 generation to similar to 97.31% in S1 generation. The plant shapes of the progeny were dramatically improved compared to the diploid parents and B.napus cv. Yangyou 6', especially for the branch initiation height, branch number and pod number. The single-plant yield was significantly improved in S1 progeny for the variations in branching sites and number. Significant improvement in plant shape and yield was observed on S2 generation compared to the local elite commercial open-pollinated cultivar, which would be further fixed by intensive selection and pyramiding breeding. Such variation is of great value for breeding rapeseed with improved plant architecture and harvest index.