Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis.
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.
Bomal
Claude
C
Centre d'Etude de Forêt, Université Laval, Québec (QC), Canada G1V 0A6. bomalc@rsvs.ulaval.ca
Bedon
Frank
F
Caron
Sébastien
S
Mansfield
Shawn D
SD
Levasseur
Caroline
C
Cooke
Janice E K
JE
Blais
Sylvie
S
Tremblay
Laurence
L
Morency
Marie-Josée
MJ
Pavy
Nathalie
N
Grima-Pettenati
Jacqueline
J
Séguin
Armand
A
Mackay
John
J
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
D010636:Phenols; D010940:Plant Proteins; D014157:Transcription Factors; D008031:Lignin