title: Characterization of a Citrus R2R3-MYB Transcription Factor that Regulates the Flavonol and Hydroxycinnamic Acid Biosynthesis.
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.
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Jianmei
authors.initials: J
authors.lastname: Long
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Kaijie
authors.initials: K
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Liu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yang
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Robert W. Holley Center for Agriculture and Health, USDA-ARS, Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, P. R. China.
authors.forename: Xiuxin
authors.initials: X
authors.lastname: Deng
mesh_terms: D002957:Citrus / Q000235:genetics* / Q000378:metabolism*; D003373:Coumaric Acids / Q000378:metabolism*; D005419:Flavonoids / Q000096:biosynthesis*; D015870:Gene Expression; D020868:Gene Silencing; D018551:Solanum lycopersicum / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D003373:Coumaric Acids; D005419:Flavonoids; D014157:Transcription Factors; C041477:3-hydroxyflavone