Rapid Genome Evolution in Polyploid Wheat

摘要

Rapid and heritable genetic and epigenetic changes were found accompanying allopolyploid formation in wheat. These changes include: (ⅰ) non-random elimination of low-copy and non-coding sequences from all but one of the constituent genomes; (ⅱ) loss and/or gain of RFLP (restriction fragment length polymorphism) bands in genomic Southern blots probed with coding or non-coding sequences; (ⅲ) cytosine methylation modification in coding genes and non-coding regions; and (ⅳ) demethylation and possible activation of retrotrans-posons. All types of changes were repeatedly found in both natural and synthetic polyploid wheat, and most of the changes showed concordant patterns, and are highly heritable. These changes were implicated to be crucial for both initial establishment (such as cytological diploidization and exclusive diploid-like meiotic behavior) and long-term adaptive evolution (such as genetic diploidization and gene functional diversification) of polyploid wheat as new species.