A significant finding of large-scale genome sequencing is that many of the genes contained in a genome exist in multiple copies or the form of families; however, little is known about their copy number or family size variation, evolution, regulation and associated biology. We previously studied that the size variation, evolution, regulation and biological association of the nucleotide-binding site (NBS)-encoding gene family in Oryza, Glycine and Gossypium (Zhang et al. 2011, Nucleic Acids Res. 38:6513-6525). Here we scrutinized the copy numbers of the NBS gene family in 61 lines or cultivars randomly selected from nine species of the genera Triticum and Aegilops. We have first examined its copy number variations among individual plants of a line, among different cultivars or lines of a species and among congeneric species. To understand the underlying mechanisms of the copy number variations of the family, we then investigated the roles of natural selection, artificial selection, polyploidization or whole-genome duplication, and plant genome size variation. Finally, we analyzed the relationships between the copy number variations of the family and plant speciation to infer their roles in biology. These results will be presented at the meeting.
YZ and XL contributed to the study equally.