Characterisation of a pine MYB that regulates lignification.
A member of the R2R3-MYB family of transcription factors was cloned from a cDNA library constructed from RNA isolated from differentiating pine xylem. This MYB, Pinus taeda MYB4 (PtMYB4), is expressed in cells undergoing lignification, as revealed by in situ RT-PCR. Electrophoretic mobility shift assays (EMSAs) showed that recombinant PtMYB4 protein is able to bind to DNA motifs known as AC elements. AC elements are ubiquitous in the promoters of genes encoding lignin biosynthetic enzymes. Transcriptional activation assays using yeast showed that PtMYB4 could activate transcription in an AC-element-dependent fashion. Overexpression of PtMYB4 in transgenic tobacco plants altered the accumulation of transcripts corresponding to genes encoding lignin biosynthetic enzymes. Lignin deposition increased in transgenic tobacco plants that overexpressed PtMYB4, and extended to cell types that do not normally lignify. Taken together, these findings are consistent with the hypothesis that PtMYB4 is sufficient to induce lignification, and that it may play this role during wood formation in pine.
Patzlaff
Astrid
A
Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
McInnis
Stephanie
S
Courtenay
Adrian
A
Surman
Christine
C
Newman
Lisa J
LJ
Smith
Caroline
C
Bevan
Michael W
MW
Mansfield
Shawn
S
Whetten
Ross W
RW
Sederoff
Ronald R
RR
Campbell
Malcolm M
MM
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D015723:Gene Library; D020570:Genes, myb / Q000235:genetics*; D008031:Lignin / Q000235:genetics; D008969:Molecular Sequence Data; D028223:Pinus / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014026:Nicotiana / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics*
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors; D008031:Lignin