Transcriptional Regulation of Wood Formation in Tree Species
Wood formation is mediated by a complex developmental program consisting of a number of sequentially occurred processes, including vascular cambial cell division, differentiation of xylem mother cells, cell elongation, secondary wall deposition, programmed cell death, and heartwood formation, all of which are proposed to be coordinated by transcriptional networks. Recent molecular and genetic studies have uncovered a transcriptional network regulating secondary wall biosynthesis during wood formation in tree species. This network encompasses a multileveled feed-forward loop regulatory structure in which the top master transcriptional switches, wood-associated NAC transcription factors (WNDs), together with WND-regulated transcription factors, regulate an array of downstream genes thereby activating the wood biosynthetic program. Genome-wide transcriptome analysis has revealed a number of wood-associated transcription factors, some of which have been proposed to be involved in vascular cambial cell division and secondary xylem differentiation. With the availability of the genome sequence data and the wood-associated gene expression data from tree species, it is expected that we will soon be able to reveal the transcriptional networks regulating various processes of wood formation, the knowledge of which could be applied to genetically engineer wood biomass composition tailored for diverse end uses such as biofuel production.
KeywordsSecondary Wall Secondary Xylem Wood Formation Transcriptional Network Coniferyl Alcohol
Work in our laboratory was supported by grants from the National Science Foundation (ISO-1051900) and the US Department of Agriculture National Institute of Food and Agriculture [AFRI Plant Biology program (#2010-65116-20468)].
- Andersson-Gunneras S, Mellerowicz EJ, Love J, Segerman B, Ohmiya Y, Coutinho PM, Nilsson P, Henrissat B, Moritz T, Sundberg B (2006) Biosynthesis of cellulose-enriched tension wood in Populus: global analysis of transcripts and metabolites identifies biochemical and developmental regulators in secondary wall biosynthesis. Plant J 45:144–165PubMedCrossRefGoogle Scholar
- Aspeborg H, Schrader J, Coutinho PM, Stam M, Kallas A, Djerbi S, Nilsson P, Denman S, Amini B, Sterky F, Master E, Sandberg G, Mellerowicz E, Sundberg B, Henrissat B, Teeri TT (2005) Carbohydrate-active enzymes involved in the secondary cell wall biogenesis in hybrid aspen. Plant Physiol 137:983–997PubMedCrossRefGoogle Scholar
- Bomal C, Bedon F, Caron S, Mansfield SD, Levasseur C, Cooke JE, Blais S, Tremblay L, Morency MJ, Pavy N, Grima-Pettenati J, Séguin A, Mackay J (2008) Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis. J Exp Bot 59:3925–3939PubMedCrossRefGoogle Scholar
- Fornalé S, Shi X, Chai C, Encina A, Irar S, Capellades M, Fuguet E, Torres JL, Rovira P, Puigdomènech P, Rigau J, Grotewold E, Gray J, Caparrós-Ruiz D (2010) ZmMYB31 directly represses maize lignin genes and redirects the phenylpropanoid metabolic flux. Plant J 64:633–644PubMedCrossRefGoogle Scholar
- Goicoechea M, Lacombe E, Legay S, Mihaljevic S, Rech P, Jauneau A, Lapierre C, Pollet B, Verhaegen D, Chaubet-Gigot N, Grima-Pettenati J (2005) EgMYB2, a new transcriptional activator from Eucalyptus xylem, regulates secondary cell wall formation and lignin biosynthesis. Plant J 43:553–567PubMedCrossRefGoogle Scholar
- Lauvergeat V, Rech P, Jauneau A, Guez C, Coutos-Thevenot P, Grima-Pettenati J (2002) The vascular expression pattern directed by the Eucalyptus gunnii cinnamyl alcohol dehydrogenase EgCAD2 promoter is conserved among woody and herbaceous plant species. Plant Mol Biol 50:497–509PubMedCrossRefGoogle Scholar
- Legay S, Sivadon P, Blervacq AS, Pavy N, Baghdady A, Tremblay L, Levasseur C, Ladouce N, Lapierre C, Séguin A, Hawkins S, Mackay J, Grima-Pettenati J (2010) EgMYB1, an R2R3 MYB transcription factor from eucalyptus negatively regulates secondary cell wall formation in Arabidopsis and poplar. New Phytol 188:774–786PubMedCrossRefGoogle Scholar
- Pavy N, Boyle B, Nelson C, Paule C, Giguère I, Caron S, Parsons LS, Dallaire N, Bedon F, Bérubé H, Cooke J, Mackay J (2008) Identification of conserved core xylem gene sets: conifer cDNA microarray development, transcript profiling and computational analyses. New Phytol 180:766–786PubMedCrossRefGoogle Scholar
- Pilate G, Guiney E, Holt K, Petit-Conil M, Lapierre C, Leplé JC, Pollet B, Mila I, Webster EA, Marstorp HG, Hopkins DW, Jouanin L, Boerjan W, Schuch W, Cornu D, Halpin C (2002) Field and pulping performances of transgenic trees with altered lignification. Nat Biotechnol 20:607–612PubMedCrossRefGoogle Scholar
- Shimizu K, Ishihara M, Ishihara T (1976) Hemicellulases of brown rotting fungus, Tyromyces palustris. II. The oligosaccharides from the hydrolysate of a hardwood xylan by the intracellular xylanase. Mokuzai Gaikkashi 22:618–625Google Scholar
- Sonbol FM, Fornalé S, Capellades M, Encina A, Touriño S, Torres JL, Rovira P, Ruel K, Puigdomènech P, Rigau J, Caparrós-Ruiz D (2009) The maize ZmMYB42 represses the phenylpropanoid pathway and affects the cell wall structure, composition and degradability in Arabidopsis thaliana. Plant Mol Biol 70:283–296PubMedCrossRefGoogle Scholar