Location: Plant, Soil and Nutrition ResearchTitle: Characterization of a citrus R2R3-MYB transcription factor that regulates the flavonol and hydroxycinnamic acid biosynthesis
|LIU, CHAOYANG - Huazhong Agricultural University|
|LONG, JIANMEI - Huazhong Agricultural University|
|ZHU, KAIJIE - Huazhong Agricultural University|
|LIU, LINLIN - Huazhong Agricultural University|
|YANG, WEI - Huazhong Agricultural University|
|ZHANG, HONGYAN - Huazhong Agricultural University|
|XU, QIANG - Huazhong Agricultural University|
|DENG, XIUXIN - Huazhong Agricultural University|
Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2016
Publication Date: 5/10/2016
Citation: Liu, C., Long, J., Zhu, K., Liu, L., Yang, W., Zhang, H., Li, L., Xu, Q., Deng, X. 2016. Characterization of a citrus R2R3-MYB transcription factor that regulates the flavonol and hydroxycinnamic acid biosynthesis. Scientific Reports. 6:25352.
Interpretive Summary: Flavonols and hydroxycinnamic acids are important phenylpropanoids that contribute to plant protection and are beneficial for human health. However, regulation of the phenylpropanoid metabolism remains elusive in plants. Citrus contains these compounds. In this study, a citrus R2R3-MYB transcription factor CsMYBF1 was isolated. Functional analysis of it in transgenic plants indicated that CsMYBF1 was involved in the regulation of the flavonol and hydroxycinnamic acid biosynthesis. CsMYBF1 was found to activate several promoters of phenylpropanoid pathway genes with MYBPLANT cis-element being the essential motif. CsMYBF1 can be served as an important gene source for engineering of the specific phenylpropanoid metabolites.
Technical Abstract: Flavonols and hydroxycinnamic acids are important phenylpropanoid metabolites in plants. In this study, we isolated and characterized a citrus R2R3-MYB transcription factor CsMYBF1, encoding a protein belonging to the flavonol-specific MYB subgroup. Ectopic expression of CsMYBF1 in tomato led to an up-regulation of a series of genes involved in primary metabolism and the phenylpropanoid pathway, and induced a strong accumulation of hydroxycinnamic acid compounds but not the flavonols. The RNAi suppression of CsMYBF1 in citrus callus caused a down-regulation of many phenylpropanoid pathway genes and reduced the contents of hydroxycinnamic acids and flavonols. Transactivation assays indicated that CsMYBF1 activated several promoters of phenylpropanoid pathway genes in tomato and citrus. Interestingly, CsMYBF1 could activate the CHS gene promoter in citrus, but not in tomato. Further examinations revealed that the MYBPLANT cis-elements were essential for CsMYBF1 in activating phenylpropanoid pathway genes. In summary, our data indicated that CsMYBF1 possessed the function in controlling the flavonol and hydroxycinnamic acid biosynthesis, and the regulatory differences in the target metabolite accumulation between two species may be due to the differential activation of CHS promoters by CsMYBF1. Therefore, CsMYBF1 constitutes an important gene source for the engineering of specific phenylpropanoid components.