Resynthesized Rapeseed (Brassica napus): Breeding and Genomics

Resynthesized rapeseed lines (2n = 4x = 38, AACC), which recreate the historical hybridization between progenitor species Brassica rapa (2n = 2x = 20, AA) and B. oleracea (2n = 2x = 18, CC) to produce Brassica napus (2n = 4x = 38, AACC), have been an important research subject for many years. These lines not only comprise useful genetic resources in rapeseed breeding for the introgression of genetic diversity and many agronomically important traits, but have also increased our understanding of how meiosis evolved in polyploid plants. In this review, we discuss and summarize how these lines have been produced via interspecific crosses over several decades and the resulting fertility and agronomically useful traits in this germplasm, as well as meiotic instability issues in these hybrids, and the putative role of meiosis genes, gene expression and other gene regulatory networks in the stabilization of meiosis. Finally, we discuss the direct use of resynthesized and semi-resynthesized Brassica napus for hybrid breeding as well as for the study of other unexplored agronomic traits of interest for the improvement of elite rapeseed cultivars.