Molecular evolution of cycloidea-like genes in Fabaceae.

The cycloidea (CYC) gene controls floral symmetry in snapdragon (Antirrhinum majus). We investigated the evolution of CYC-like genes in some species of legumes that have zygomorphic flowers. Two to four CYC-like genes were isolated from a single species. The results of NJ and ML analyses indicate that CYC-like genes in legumes group into two monophyletic clades; one group consists of eight CYC-like genes (Clade 1) and the other contains three CYC-like genes and TB1 of maize (Clade 2). These phylogenetic trees and the Shimodaira-Hasegawa test suggest that Clade 1 is a sister of the original CYC group (Clade 3). Moreover, the result of the GeneTree analysis showed that the CYC-like genes experienced repeated duplication events during the evolution of legumes. We herein speculate as to the role of CYC-like genes in legumes and discuss the evolutionary processes that these genes have undergone.