The broad diversity of flowers in Fabaceae provides a good system to investigate the development and evolution of floral symmetry in higher plants. Many studies have demonstrated a conserved mechanism controlling the development of zygomorphic flowers during the last decades. However, the molecular basis of how asymmetric flower is established is largely unknown. In this study, we characterized mutants named keeled wings in mungbean, which is a legume species with asymmetric flowers.
Compared to those in the wild-type plants, the lateral petals were ventralized in the kw (keeled wings) mutants. Map-based cloning showed that KW was the VrCYC3 gene in mungbean, the ortholog of Lotus japonicus CYC3 ( LjCYC3 ) and Pisum sativum CYC3 ( PsCYC3 ). In addition, another two CYC-like genes named VrCYC1 and VrCYC2 were identified from the mungbean genome. The three CYC-like genes displayed distinct expression patterns in dorsal, lateral, and ventral petals. It was found that VrCYC3 was located in the nucleus. Further analysis showed that VrCYC3 had transcription activity and could interact with VrCYC1 and VrCYC2 in a yeast cell.
Moreover, the deletion of two amino acid residues in the R domain of VrCYC3 protein could decrease its interaction with VrCYC1 and VrCYC2 proteins. The results suggest that LjCYC3/VrCYC3 orthologs play conserved roles in determining the lateral petal shape and identity of a zygomorphic flower as well as the asymmetric flower in Papilionoideae.
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Li, Xin & Sun, Mingzhu & Jia, Yahui & Qiu, Dan & Peng, Qincheng & Zhuang, Lili. (2022). Genetic control of the lateral petal shape and identity of asymmetric flowers in mungbean (Vigna radiata L.). Frontiers in Plant Science. 13. 10.3389/fpls.2022.996239.