Canadian Forest Service Publications

Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis. 2008. Bomal, C.; Bedon, F.; Caron, S.; Mansfield, S.D.; Levasseur, C.; Cooke, J.E.; Blais, S.; Tremblay, L.; Morency, M.-J.; Pavy, N.; Grima-Pettenati, J.; Séguin, A.; MacKay, J. J. Exp. Bot. 59(14): 3925-3939.

Year: 2008

Issued by: Laurentian Forestry Centre

Catalog ID: 39611

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1093/jxb/ern234

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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 _MYB_s 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.