A truncated MYB transcription factor from Antirrhinum majus regulates epidermal cell outgrowth

Abstract

Plant MYB genes can be divided into subgroups on the basis of additional conserved regions of sequence. In some cases, genes within a subgroup share similarities in function, as well as sequence. The functions of three proteins in subgroup 9 have been described, with AmMYBMX regulating the differentiation of conical-papillate petal epidermal cells, PhMYB1 involved in extending the growth of these cells, and AmMYBML1 involved in differentiation of several petal epidermal cell types. Here, the isolation of a gene encoding a new member of MYB subgroup 9, AmMYBML3 (Antirrhinum majus MYB MIXTA-LIKE 3) is described, which contains the defining regions of conserved sequence but is lacking the majority of the C-terminus, including the amphipathic alpha-helix presumed necessary for transcriptional activation. AmMYBML3 is expressed in all aerial organs, but its expression is restricted to outgrowing epidermal cells, including trichomes, stigmatic papillae, and petal conical-papillate cells. Ectopic expression of AmMYBML3 in tobacco results in the formation of conical-papillate cells in the usually flat carpel epidermis. These data suggest that this protein is capable of altering epidermal development, thus resulting in cellular outgrowth, despite the missing C-terminus, and may act in conjunction with other transcriptional activators to enhance cellular outgrowth from the epidermis of all aerial organs.

MIXTA-Like Transcription Factors and WAX INDUCER1/SHINE1 Coordinately Regulate Cuticle Development inArabidopsisandTorenia fournieri

“…The Role of MIXTA-Like MYBs in Cuticle Development in the Context of Epidermal Cell Differentiation MIXTA-like MYBs from snapdragon, petunia, and Arabidopsis are known to regulate epidermal cell specification, morphology, and maturation; their roles in trichomes and petal epidermal cells are particularly well studied (Noda et al, 1994;Folkers et al, 1997;Glover et al, 1998;Baumann et al, 2007;Jaffé et al, 2007;Jakoby et al, 2008). Our results from chimeric repressor, activator, and knockout/down experiments also supported the above-mentioned functions of MIXTA-like MYBs (see Supplemental Tables 5 and 6 online).…”

“…Mutation of MIXTA or petunia (Petunia hybrida) MYB1 prevents anticlinal growth of petal epidermal cells, resulting in altered intensity of petal color (Noda et al, 1994;Glover et al, 1998;Jaffé et al, 2007;Baumann et al, 2007). Another snapdragon MIXTA-like gene, MYBML1, which is expressed in specialized petal trichomes, induced ectopic differentiation of trichomes on carpels when it was overexpressed (Perez-Rodriguez et al, 2005).…”

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…In addition to trichome-specific EST resources, numerous glandular trichome-specific gene promoters have been reported in the literature for a variety of plants, including (but not restricted to) Antirrhinum majus, A. annua, C. sativus, H. lupulus, Mentha spp., N. tabacum, S. lycopersicum, and S. habrochaites (Okada and Ito, 2001;Wang et al, 2002Wang et al, , 2011Wang et al, , 2013Gutiérrez-Alcalá et al, 2005;Liu et al, 2006;Jaffé et al, 2007;Kim et al, 2008;Shangguan et al, 2008;Ennajdaoui et al, 2010;Choi et al, 2012;Sallaud et al, 2012;Spyropoulou et al, 2014;Kortbeek et al, 2016;Laterre et al, 2017;Vining et al, 2017;for review, see Tissier, 2012b). It is worth noting that most of these trichome-specific promoters are active in mature glandular trichomes (mostly in glandular cells at the tip of the trichome).…”

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

“…2 Other MIXTA homologs in A. majus and petunia promote anticlinal expansion of epidermal cells, as shown by analysis of mutants and overexpression lines. [3][4][5] Overexpression of MYB16, an Arabidopsis MIXTA homolog, induced similar ectopic outgrowths in petals of Arabidopsis and tobacco, suggesting it has similar functions to petunia MYB1 and A. majus MYBML2. 4 Another Arabidopsis homolog, MYB106/NOK, regulates trichome maturation, including promotion and limitation of trichome branching.…”