MYB Family from Maize
Required domains for MYB family:PF00249
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The first MYB gene identified was the "oncogene" v-Myb derived from the avian myeloblastosis virus and later the corresponding human cellular homolog c-Myb was identified. Classical MYB factors, which are related to c-Myb, seem to be involved in the control of the cell cycle in animals, plants and other higher eukaryotes.
MYB factors represent a very large and diverse gene family where proteins with two MYB repeats (R2R3, each approximately 50 aa long) are the most common ones, but proteins with just one repeat or three or four repeats are found, too. Each motif consists of three alpha-helices, where the second and third form a helix-turn-helix structure, and the third helix is thought to make contact with the major groove of DNA. Three tryptophan residues in each repeat, spaced by 18-21 aa, form a very conserved cluster among all MYB factors. Compared to the highly conserved MYB domain, other regions in MYB proteins can be highly variable.
Today, more than 200 MYB factors are identified in maize (Zea mays) and rice (Oryza sativa) and a comparably high number in other related monocots. Structurally and functionally very diverse MYB factors can be involved in the control of mainly plant specific processes such as plant secondary metabolism, cell morphogenesis or cell fate (Wu et al., 2022).
The first plant MYB gene C1 (ZmMYB1) was isolated from maize, which encodes a c-MYB-like transcription factor. C1 regulates the Bz1 and A1 structural genes involved in anthocyanin biosynthesis by (Paz-Ares et al., 1986, Cone et al., 1986, Paz-Ares et al., 1987, Martin et al., 1997). C1 was found to depend on the basic helix-loop-helix (bHLH) proteins R (ZmbHLH1) or B (ZmbHLH2) for regulatory function, whereas the closely related Myb protein P1 (ZmMYB3) does not (Grotewold et al., 2000, Dias et al., 2003). Interestingly, P1 is also highly expressed in leaves of maize landraces adapted to high altitudes and higher levels of UV-B radiation. Epigenetic regulation is involved as supported by the observation that DNA methylation in the P1 proximal promoter, intron1 and intron2 is decreased by UV-B in all high altitude lines analyzed (Rius et al., 2016, Li et al., 2022). It has been recognized that MYB factors play a prominent role in regulation of anthocyanin biosynthesis and secondary metabolism in all plant species (Cao et al., 2020, Yan et al., 2021).
The MYB-CC gene family encode proteins that harbor a combination of characteristic myeloblastosis (MYB) and coiled-coil (CC) domain structures. Some MYB-CC genes have been demonstrated to represent transcription factors regulating phosphate uptake and controlling the starvation response in plants. A total of 12 maize MYB-CC genes (ZmMYB-CC1 to ZmMYB-CC12) were identified located in six out of the 10 chromosomes of maize (Bai et al., 2019).
Last updated June 2023 by John Gray
Qiang Z, Sun H, Ge F, Li W, Li C, Wang S, Zhang B, Zhu L, Zhang S, Wang X, Lai J, Qin F, Zhou Y, Fu Y. The transcription factor ZmMYB69 represses lignin biosynthesis by activating ZmMYB31/42 expression in maize. Plant Physiol. 2022 Aug 1;189(4):1916-1919. doi: 10.1093/plphys/kiac233. PMID: 35640133; PMCID: PMC9343001.
Xiao R, Zhang C, Guo X, Li H, Lu H. MYB Transcription Factors and Its Regulation in Secondary Cell Wall Formation and Lignin Biosynthesis during Xylem Development. Int J Mol Sci. 2021 Mar 30;22(7):3560. doi: 10.3390/ijms22073560. PMID: 33808132; PMCID: PMC8037110.
Wu Y, Wen J, Xia Y, Zhang L, Du H. Evolution and functional diversification of R2R3-MYB transcription factors in plants. Hortic Res. 2022 Mar 8;9:uhac058. doi: 10.1093/hr/uhac058. PMID: 35591925; PMCID: PMC9113232.
Bai J, Sun F, Wang M, Su L, Li R, Caetano-Anollés G. Genome-wide analysis of the MYB-CC gene family of maize. Genetica. 2019 Feb;147(1):1-9. doi: 10.1007/s10709-018-0042-y. Epub 2018 Sep 21. Erratum in: Genetica. 2018 Oct 31;: PMID: 30242535.
Li C, Yu W, Xu J, Lu X, Liu Y. Anthocyanin Biosynthesis Induced by MYB Transcription Factors in Plants. Int J Mol Sci. 2022 Oct 2;23(19):11701. doi: 10.3390/ijms231911701. PMID: 36233003; PMCID: PMC9570290.
Martin C, Paz-Ares J. MYB transcription factors in plants. Trends Genet. 1997 Feb;13(2):67-73. doi: 10.1016/s0168-9525(96)10049-4. PMID: 9055608.
Mondal SK, Roy S. Genome-wide sequential, evolutionary, organizational and expression analyses of phenylpropanoid biosynthesis associated MYB domain transcription factors in Arabidopsis. J Biomol Struct Dyn. 2018 May;36(6):1577-1601. doi: 10.1080/07391102.2017.1329099. Epub 2017 Jun 2. PMID: 28490275.
Cao Y, Li K, Li Y, Zhao X, Wang L. MYB Transcription Factors as Regulators of Secondary Metabolism in Plants. Biology (Basel). 2020 Mar 24;9(3):61. doi: 10.3390/biology9030061. PMID: 32213912; PMCID: PMC7150910.
Du H, Feng BR, Yang SS, Huang YB, Tang YX. The R2R3-MYB transcription factor gene family in maize. PLoS One. 2012;7(6):e37463. doi: 10.1371/journal.pone.0037463. Epub 2012 Jun 7. PMID: 22719841; PMCID: PMC3370817.
Paz-Ares J, Ghosal D, Wienand U, Peterson PA, Saedler H. The regulatory c1 locus of Zea mays encodes a protein with homology to myb proto-oncogene products and with structural similarities to transcriptional activators. EMBO J. 1987 Dec 1;6(12):3553-8. doi: 10.1002/j.1460-2075.1987.tb02684.x. PMID: 3428265; PMCID: PMC553820.
Paz-Ares J, Wienand U, Peterson PA, Saedler H. Molecular cloning of the c locus of Zea mays: a locus regulating the anthocyanin pathway. EMBO J. 1986 May;5(5):829-33. doi: 10.1002/j.1460-2075.1986.tb04291.x. PMID: 15957214; PMCID: PMC1166870.
Cone KC, Burr FA, Burr B. Molecular analysis of the maize anthocyanin regulatory locus C1. Proc Natl Acad Sci U S A. 1986 Dec;83(24):9631-5. doi: 10.1073/pnas.83.24.9631. PMID: 3025847; PMCID: PMC387194.
Grotewold E, Sainz MB, Tagliani L, Hernandez JM, Bowen B, Chandler VL. Identification of the residues in the Myb domain of maize C1 that specify the interaction with the bHLH cofactor R. Proc Natl Acad Sci U S A. 2000 Dec 5;97(25):13579-84. doi: 10.1073/pnas.250379897. PMID: 11095727; PMCID: PMC17618.
Rius SP, Emiliani J, Casati P. P1 Epigenetic Regulation in Leaves of High Altitude Maize Landraces: Effect of UV-B Radiation. Front Plant Sci. 2016 Apr 21;7:523. doi: 10.3389/fpls.2016.00523. PMID: 27148340; PMCID: PMC4838615.
Yan H, Pei X, Zhang H, Li X, Zhang X, Zhao M, Chiang VL, Sederoff RR, Zhao X. MYB-Mediated Regulation of Anthocyanin Biosynthesis. Int J Mol Sci. 2021 Mar 18;22(6):3103. doi: 10.3390/ijms22063103. PMID: 33803587; PMCID: PMC8002911.
Dias AP, Braun EL, McMullen MD, Grotewold E. Recently duplicated maize R2R3 Myb genes provide evidence for distinct mechanisms of evolutionary divergence after duplication. Plant Physiol. 2003 Feb;131(2):610-20. doi: 10.1104/pp.012047. PMID: 12586885; PMCID: PMC166837.