The R2R3-MYB proteins comprise one of the largest families of transcription factors in plants. For example, the arabidopsis genome encodes over 120 different R2R3-MYB proteins. R2R3-MYB proteins have been implicated in the regulation of both developmental and biochemical processes in plants, particularly the terminal differentiation of epidermal cells and the control of phenylpropanoid metabolism. Given the size of the R2R3-MYB family and the fact that members of this family have demonstrable roles in the regulation of phenylpropanoid metabolism and terminal cellular differentiation, the Campbell lab hypothesised that a subset of R2R3-MYB proteins might regulate aspects of xylem formation. Xylem formation, or xylogenesis, is an essential process in the growth, development and evolution of land plants. Xylogenesis is comprised of a set of overlapping events of terminal cellular differentiation: cell division, cell elongation, cell wall thickening, lignification, and autolysis. As related events have been shown to involve transcriptional regulation by R2R3-MYB proteins in other cell types, R2R3-MYB proteins may also regulate some of these events during xylogenesis. In order to test this hypothesis, Dr. Campbell and his group have isolated, characterised, and investigated the roles of R2R3-MYB transcription factors that are expressed during xylem development.

The Campbell lab have used a multi-faceted approach to examine MYB activity, including: in vitro biochemical assays, such as elecrophoretic mobility shift assays and surface plasmon resonance; functional assays using yeast; transient transcriptional activation assays in plant cells; stable genetic modification of arabidopsis, tobacco, poplar and spruce; in situ PCR; promoter::reporter fusion analysis of gene expression; mutant analysis using arabidopsis; metabolic profiling of transgenic and mutant plants; and transcript profiling of transgenic and mutant plants using complete arabidopsis genome microarrays. These studies are generating comprehensive pictures of the regulation and function of individual MYB family members, and shedding light on the evolution of this important family of transcriptional regulators. A series of papers based on this work is emerging from the lab, based largely on completed Ph.D. theses and undergraduate research project dissertations.

Personnel:

Dr. Christian Dubos

Publications

Patzlaff A, Newman LJ, Dubos C, Whetten RW, Smith C, McInnis S, Bevan M, Sederoff RR, Campbell MM (2003) Characterisation of PtMYB1, an R2R3-MYB from pine xylem. Plant Molecular Biology 53:597-608 (BBSRC funded)

Patzlaff A, McInnis S, Courtenay A, Surman C, Newman LJ, Smith C, Bevan M, Mansfield S, Sederoff RR, Whetten RW, Campbell MM (2003) Characterisation of a pine MYB that regulates lignification. The Plant Journal 36: 743-754, doi:10.1046/j.1365-313X.2003.01916.x (BBSRC funded)

Gómez-Maldonado J, Avila C, de la Torre F, Cañas R, Cánovas F, Campbell MM (2004) Functional interactions between a glutamine synthetase promoter and MYB proteins. The Plant Journal (in press) doi:10.1111/j.1365-313X.2004.02153.x (BBSRC funded)