EVOLUTIONARY HISTORY OF THE ANGIOSPERMS AND ITS RELEVANCE TO BRASSICA

One of the more surprising discoveries in the sequences of Arabidopsis and rice has been that both are ancient polyploids, in the case of Arabidopsis involving at least two and perhaps three duplications of most of the genome. Ancient whole-genome duplication and subsequent loss of many of the duplicated gene copies appears to contribute substantially to deviations from co-linearity and/or synteny that are observed in many angiosperm lineages. The Brassica genomes are shaped not only by these ancient polyploidization events shared with Arabidopsis, but by 1-2 additional events in the 'diploid' Brassicas and the recent formation of new polyploid species. An important dimension in clarifying the evolutionary history of the Brassica genus is the better resolution of the timing and consequences of polyploidizations since the Brassica-Arabidopsis divergence. Early efforts to assess the predictive value of Arabidopsis data for determining fates of duplicated Brassica genes will be discussed.