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

Author: Jaff Felix W.   Tattersall Alexander   Glover Beverley J.  

Publisher: Oxford University Press

ISSN: 1460-2431

Source: Journal of Experimental Botany, Vol.58, Iss.6, 2007-04, pp. : 1515-1524

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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 -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.

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