P2-2
NAC-MYB-BASED TRANSCRIPCIONAL NETWORK
INVOLVED IN THE REGULATION OF PHENYLALANINE
BIOSYNTHESIS IN P. PINASTER
Mª Belén Pascual, Rafael A. Cañas, Blanca Craven-Bartle,
Francisco M. Cánovas and Concepción Ávila
Departamento de Biología Molecular y Bioquímica. Facultad de Ciencias.
Universidad de Málaga. Campus de teatinos s/n, Málaga, Spain
Email: cavila@uma.es
Conifer trees divert large quantities of carbon into the biosynthesis of
phenylpropanoids, particularly to generate lignin, an important
constituent of wood. Since phenylalanine is the precursor for
phenylpropanoid biosynthesis, the precise regulation of
phenylalanine synthesis and use should occur simultaneously. This
crucial pathway is finely regulated primarily at the transcriptional
level. Transcriptome analyses indicate that the transcription factors
(TFs) preferentially expressed during wood formation in plants
belong to the MYB and NAC families. Craven-Bartle et al. (2013)
have shown that Myb8 is a candidate regulator of key genes in
phenylalanine biosynthesis involved in the supply of the
phenylpropane carbon skeleton necessary for lignin biosynthesis.
This TF is able to bind AC elements present in the promoter regions
of these genes to activate transcription. In Arabidopsis, the
transcriptional network controlling secondary cell wall involves
NAC-domain regulators operating upstream Myb transcription
factors. We have identified in the P. pinaster genome three NAC
proteins as potential candidates to be involved in vascular
development. One of them, PpNAC1 is expressed both in xylem and
compression wood from adult trees and has been thoroughly
characterized. Its role upstream the transcriptional network
involving Myb8 will be discussed. The understanding of the
transcriptional regulatory network associated to phenylpropanoids
and lignin biosynthesis in conifers is crucial for future applications in
tree improvement and sustainable forest management.
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