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Abstract Detail


Phytochemical Section

Tuominen, Lindsey K. [1], Payyavula, Raja S. [2], Harding, Scott A. [1], Tsai, Chung-Jui [3].

Perturbation of Populus Phenylpropanoid Metabolism in Suspension Cell Cultures.

Populus secondary metabolism is characterized by a diversity of phenylpropanoid compounds that can collectively account for up to 30% of leaf dry mass. The various classes of these compounds are thought to derive from separate, potentially competing biosynthetic branch pathways. To develop a better understanding of phenylpropanoid partitioning and the impact of this pathway on primary metabolic processes, we subjected heterotrophic suspension cell cultures of P. tremuloides to a series of feeding experiments. Methyl jasmonate (MeJA) was used as a defense elicitor to stimulate phenylpropanoid metabolism with varying constraints in the core pathway imposed by one of three metabolic inhibitors: piperonylic acid (PIP) for cinnamate-4-hydroxylase, α-aminooxy-β-phenylpropionic acid (AOPP) for phenylalanine ammonia lyase, and methylenedioxycinnamic acid (MDCA) for 4-coumaroyl:CoA ligase. Cells were sampled 48 h after treatment and analyzed by metabolite profiling using GC-MS and LC-MS, as well as by colorimetric quantification of condensed tannins. Core phenylpropanoid metabolites showed changes broadly consistent with expected enzyme inhibition, with increases in phenylalanine in AOPP-treated cells and cinnamicacid in PIP-treated cells. Interestingly, MDCA-treated cells did not show increases in coumaric acid as expected, but cinnamic acid levels were strongly increased, suggestinga possible feedback mechanism in the pathway. Flavonoid derivatives, including condensed tannins, generally showed additive rather than interactive effects between elicitation and inhibition. Several amino acids also showed strong increases under AOPP treatment, while PIP and MDCA treatments had only subtle impacts. Citric acid cycle metabolites did not appear to be strongly affected by the inhibitors but did respond to elicitation. Overall, the results provide metabolic evidence for possible linkage between phenylpropanoid and amino acid metabolism, supporting previous suggestions of cross-talk between carbon and nitrogen metabolism via phenylalanine-N cycling.

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1 - The University of Georgia, Warnell School of Forestry & Natural Resources, 180 E Green St, Athens, GA, 30602, USA
2 - Michigan Technological University, School of Forest Resources & Environmental Science, 1400 Townsend Drive, Houghton, MI, 49931, USA
3 - The University of Georgia, Department of Genetics/Warnell School of Forestry & Natural Resources, 180 E Green St, Athens, GA, 30602, USA

Keywords:
phenylpropanoids
metabolic profiling
Populus.

Presentation Type: Oral Paper:Papers for Sections
Session: 50
Location: Lindell B/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 1:30 PM
Number: 50001
Abstract ID:33


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