Article

Floral zygomorphy is proved to have evolved many times independently from actinomorphy, exhibiting two kinds of asymmetry, dorsoventral (DV) and organ internal (IN) asymmetry, in flowering plants. Multiple underlying regulators are involved in establishing the complex flowering mechanism during plant development. To understand how genes control the floral dorsoventral asymmetry in soybean, we isolated and analyzed the role of two different copies of CYC-like genes in Glycine max. It was demonstrated that CYC-like genes, GmTCP1 and GmTCP2, encoded the TCP transcription factors that were specifically expressed in the dorsal region of floral meristem. However, the two copies were proved to be functionally divergent during petal development, and by altering the expression of CYC-like genes in transgenic soybean, similar to CYC and DICH, it was found that CYC-like genes had dorsalizing activity. The expression pattern of transgenic plants indicated that the GmTCP2 gene could specifically regulate downstream target genes such as RAD-like and DIV-like genes in the dorsal, lateral and the ventral petals. The relative expression of CUC1 and CUC2 varied in the three different kinds of petals: it was high in the dorsal petals, but low in the ventral petals. At the same time, the expression level of GmTCP1 and GmTCP2 was equally very low. In addition, the study of transgenic Arabidopsis showed that GmTCP2 could play a significant role in cell division during the whole development of plants.