To date, several genetic diversity and population structure studies have been performed and published for domesticated B. oleracea, but some have been limited by low numbers of markers. More importantly, very few have included all the described B. oleracea morphotypes, and the ones that are included are often represented by a small number of accessions. What is generally lacking in these studies is data on genetic comparisons between modern hybrids and old landrace accessions.
Recently, scientists from Wageningen University analyzed the genetic diversity, genealogical relationships, and population structure among 912 accessions of B. oleracea and their wild relatives. They found that genetic diversity decreased from genebank accessions to modern hybrid accessions. Phylogenetic analysis showed evidence for two domestication lineages, the leafy head lineage (LHL) and the arrested inflorescence lineage (AIL), that arose with the onset of diversification and breeding of cabbages and cauliflowers around 400 BC in the Middle East. Different kales and wild B. oleracea were the likely progenitors of the diverse lineages (which include sprouts and kohlrabi in addition to AIL and LHL).
“Cauliflower is the least diverse morphotype and has the strongest genetic differentiation with other morphotypes, which points to a very strong genetic bottleneck. Genetic diversity reduced from landraces to modern hybrids for almost all morphotypes,” Dr. Guusje Bonnema said. This comprehensive Brassica C-group germplasm collection provides valuable genetic resources and a sound basis for B. oleracea breeding.
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