XVI International Botanical Congess

Genetic maps of a broad range of organisms indicate that diploid species often contain duplicated chromosomal regions. These duplicated regions are presumably the remnants of ancient polyploid events. Despite the prevalence of these duplications, there have been few attempts to infer the mode and timing of the original polyploid event or to examine the pattern of chromosomal rearrangement during re-diploidization. DNA sequence data from duplicated chromosomal regions of maize provide detailed information about the mode and timing of an ancient polyploid event, suggesting that maize underwent an allopolyploid event roughly 11.4 million years ago between species that diverged roughly 20.5 million years ago. Genetic maps of maize provide additional insight into the extent and pattern of chromosomal rearrangement during the process of re-diploidization.