title: Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis.
abstract: The involvement of two R2R3-MYB genes from Pinus taeda L., PtMYB1 and PtMYB8, in phenylpropanoid metabolism and secondary cell wall biogenesis was investigated in planta. These pine MYBs were constitutively overexpressed (OE) in Picea glauca (Moench) Voss, used as a heterologous conifer expression system. Morphological, histological, chemical (lignin and soluble phenols), and transcriptional analyses, i.e. microarray and reverse transcription quantitative PCR (RT-qPCR) were used for extensive phenotyping of MYB-overexpressing spruce plantlets. Upon germination of somatic embryos, root growth was reduced in both transgenics. Enhanced lignin deposition was also a common feature but ectopic secondary cell wall deposition was more strongly associated with PtMYB8-OE. Microarray and RT-qPCR data showed that overexpression of each MYB led to an overlapping up-regulation of many genes encoding phenylpropanoid enzymes involved in lignin monomer synthesis, while misregulation of several cell wall-related genes and other MYB transcription factors was specifically associated with PtMYB8-OE. Together, the results suggest that MYB1 and MYB8 may be part of a conserved transcriptional network involved in secondary cell wall deposition in conifers.
authors.affiliation: Centre d'Etude de Forêt, Université Laval, Québec (QC), Canada G1V 0A6. bomalc@rsvs.ulaval.ca
authors.forename: Claude
authors.initials: C
authors.lastname: Bomal
authors.forename: Frank
authors.initials: F
authors.lastname: Bedon
authors.forename: Sébastien
authors.initials: S
authors.lastname: Caron
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Mansfield
authors.forename: Caroline
authors.initials: C
authors.lastname: Levasseur
authors.forename: Janice E K
authors.initials: JE
authors.lastname: Cooke
authors.forename: Sylvie
authors.initials: S
authors.lastname: Blais
authors.forename: Laurence
authors.initials: L
authors.lastname: Tremblay
authors.forename: Marie-Josée
authors.initials: MJ
authors.lastname: Morency
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pavy
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Grima-Pettenati
authors.forename: Armand
authors.initials: A
authors.lastname: Séguin
authors.forename: John
authors.initials: J
authors.lastname: Mackay
mesh_terms: D002473:Cell Wall / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D008031:Lignin / Q000378:metabolism; D008969:Molecular Sequence Data; D010636:Phenols / Q000378:metabolism; D052585:Phloem / Q000378:metabolism; D028222:Picea / Q000235:genetics / Q000378:metabolism*; D041603:Pinus taeda / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D010636:Phenols; D010940:Plant Proteins; D014157:Transcription Factors; D008031:Lignin