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Abstract Detail

Biochemistry, metabolism, carbon flux

Schuetz, Mathias [1], Smith, Rebecca [1], Ellis, Brian [2], Samuels, Lacey [1].

Upregulation of Arabidopsis thaliana MYB58/63 transcription factors affects both intracellular and extracellular phenylpropanoid metabolites.

Lignin provides strength and rigidity to the secondary cell walls of tracheary elements and fibres in vascular plants. The Arabidopsis transcription factors MYB58 and MYB63 have been shown to upregulate gene expression related to the monolignol biosynthesis branch of the phenylpropanoid pathway, and are necessary for secondary cell wall lignification. In this study, the broader metabolic consequences of upregulating monolignol biosynthesis are defined. In Arabidopsis plants over-expressing MYB58 or MYB63 (Pro35S:MYB58 or Pro35S:MYB63), large amounts of intracellular phenolics accumulated, which could be localized to vacuoles and vacuolar inclusions by live-cell imaging under UV light. Analysis of methanolic extracts from Pro35S:MYB53 or Pro35S:MYB63 plant leaves revealed an increased accumulation of sinapoyl esters and the appearance of monolignol glucosides. Subsequent analysis of the leaf cells after extraction of soluble phenolics revealed UV autofluorescence of primary cell walls thereby suggesting ectopic lignification. These data indicate that plant cells respond to ectopic monolignol production by both exporting monolignols to the cell wall for polymerization and producing monolignol glucosides and sinapoyl esters for vacuolar storage. We continued our analysis of the Pro35S:MYB63 system by attempting to modify the intracellular monolignol glucosides pool and extracellular lignin by co-overexpressing candidate monolignol export proteins or oxidative enzymes in Pro35S:MYB63 plants. The results are presented in the context of current cell wall lignification models and provide insight into how plant cells respond to high metabolic flux through the monolignol biosynthesis pathway.

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1 - University of British Columbia, Department of Botany, 6270 University Boulevard, Vancouver, BC, V6T1Z4, Canada
2 - University of British Columbia, Michael Smith Laboratories, 2185 East Mall, Vancouver, BC, V6T1Z4, Canada

Phenylpropanoid biosynthesis
monolignol glucoside.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PBC006
Abstract ID:1319
Candidate for Awards:None

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