Please use this identifier to cite or link to this item: https://doi.org/10.1093/jxb/ert310
Title: A bacterial quercetin oxidoreductase quoa-mediated perturbation in the phenylpropanoid metabolic network increases lignification with a concomitant decrease in phenolamides in arabidopsis
Authors: Reuben, S. 
Rai, A.
Pillai, B.V.S.
Rodrigues, A.
Swarup, S. 
Keywords: Anthocyanins
Auxotrophic mutant
Branch points
Flavonoids
Lignin pathway
Metabolomics
PGPR
Plant-growthpromoting rhizobacteria
Issue Date: 2013
Citation: Reuben, S., Rai, A., Pillai, B.V.S., Rodrigues, A., Swarup, S. (2013). A bacterial quercetin oxidoreductase quoa-mediated perturbation in the phenylpropanoid metabolic network increases lignification with a concomitant decrease in phenolamides in arabidopsis. Journal of Experimental Botany 64 (16) : 5183-5194. ScholarBank@NUS Repository. https://doi.org/10.1093/jxb/ert310
Abstract: Metabolic perturbations by a gain-of-function approach provide a means to alter steady states of metabolites and query network properties, while keeping enzyme complexes intact. A combination of genetic and targeted metabolomics approach was used to understand the network properties of phenylpropanoid secondary metabolism pathways. A novel quercetin oxidoreductase, QuoA, from Pseudomonas putida, which converts quercetin to naringenin, thus effectively reversing the biosynthesis of quercetin through a de novo pathway, was expressed in Arabidopsis thaliana. QuoA transgenic lines selected for low, medium, and high expression levels of QuoA RNA had corresponding levels of QuoA activity and hypocotyl coloration resulting from increased anthocyanin accumulation. Stems of all three QuoA lines had increased tensile strength resulting from increased lignification. Sixteen metabolic intermediates from anthocyanin, lignin, and shikimate pathways had increased accumulation, of which 11 paralleled QuoA expression levels in the transgenic lines. The concomitant upregulation of the above pathways was explained by a significant downregulation of the phenolamide pathway and its precursor, spermidine. In a tt6 mutant line, lignifications as well as levels of the lignin pathway metabolites were much lower than those of QuoA transgenic lines. Unlike QuoA lines, phenolamides and spermidine were not affected in the tt6 line. Taken together, these results suggest that phenolamide pathway plays a major role in directing metabolic intermediates into the lignin pathway. Metabolic perturbations were accompanied by downregulation of five genes associated with branch-point enzymes and upregulation of their corresponding products. These results suggest that gene-metabolite pairs are likely to be co-ordinately regulated at critical branch points. Thus, these perturbations by a gain-of-function approach have uncovered novel properties of the phenylpropanoid metabolic network. © The Author 2013.
Source Title: Journal of Experimental Botany
URI: http://scholarbank.nus.edu.sg/handle/10635/92848
ISSN: 00220957
DOI: 10.1093/jxb/ert310
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