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Eg MYB2, a new transcriptional activator from Eucalyptus xylem, regulates secondary cell wall formation and lignin biosynthesis
Author(s) -
Goicoechea Monica,
Lacombe Eric,
Legay Sylvain,
Mihaljevic Snjezana,
Rech Philippe,
Jauneau Alain,
Lapierre Catherine,
Pollet Brigitte,
Verhaegen Daniel,
ChaubetGigot Nicole,
GrimaPettenati Jacqueline
Publication year - 2005
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2005.02480.x
Subject(s) - monolignol , cinnamyl alcohol dehydrogenase , myb , secondary cell wall , biology , phenylpropanoid , lignin , xylem , gene , promoter , biochemistry , cell wall , secondary metabolism , transcription factor , biosynthesis , botany , gene expression
Summary Eg MYB2, a member of a new subgroup of the R2R3 MYB family of transcription factors, was cloned from a library consisting of RNA from differentiating Eucalyptus xylem. EgMYB2 maps to a unique locus on the Eucalyptus grandis linkage map and co‐localizes with a quantitative trait locus (QTL) for lignin content. Recombinant Eg MYB2 protein was able to bind specifically the cis ‐regulatory regions of the promoters of two lignin biosynthetic genes, cinnamoyl‐coenzyme A reductase ( CCR ) and cinnamyl alcohol dehydrogenase ( CAD ), which contain MYB consensus binding sites. Eg MYB2 was also able to regulate their transcription in both transient and stable expression assays. Transgenic tobacco plants over‐expressing EgMYB2 displayed phenotypic changes relative to wild‐type plants, among which were a dramatic increase in secondary cell wall thickness, and an alteration of the lignin profiles. Transcript abundance of genes encoding enzymes specific to lignin biosynthesis was increased to varying extents according to the position of individual genes in the pathway, whereas core phenylpropanoid genes were not significantly affected. Together these results suggest a role for Eg MYB2 in the co‐ordinated control of genes belonging to the monolignol‐specific pathway, and therefore in the biosynthesis of lignin and the regulation of secondary cell wall formation.