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Abstract Detail


Secondary Metabolism

Rehak, Ludmila [1], Jander, Georg [2].

Biosynthesis of meta-tyrosine in fescue.

meta-Tyrosine is an allelochemical secreted by chewing’s fescue (Festuca rubra ssp. commutata). A non-protein amino acid, meta-tyrosine has been found to inhibit growth of a broad range of plant species. Besides occurring naturally in several fine leaf fescues, it has been found in only one other plant species, Euphorbia myrsinites. Its simple structure, potency, broad span of toxicity, and rarity make meta-tyrosine an appealing candidate as a bioherbicide. Natural-derived herbicides are growing in popularity as environmental and health concerns mount over widespread application of synthetic herbicides. meta-Tyrosine is found at a ten-fold higher concentration in roots than in other parts of fescue, suggesting an underground release route. To elucidate the biochemical pathway of meta-tyrosine synthesis, fescue was grown hydroponically with labeled precursors, and isotopically labeled meta-tyrosine was detected by GC-MS and LC-MS. All labeled carbon and nitrogen atoms of [U-13C -15N]phenylalanine were incorporated into meta-tyrosine, suggesting that it is synthesized by a phenylalanine hydroxylase. Interestingly, HPLC assays showed that exogenously added shikimate increases meta-tyrosine accumulation more so than phenylalanine. To date, attempts to isolate enzymatic activity from homogenized tissue have failed. Construction of a F. rubra root cDNA library is underway for identification of possible genes encoding phenylalanine hydroxylases.


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1 - Boyce Thompson Institute, Jander Lab, Tower Road, Ithaca, NY, 14850, USA
2 - Boyce Thompson Institute, Jander Lab

Keywords:
allelopathy
fescue
meta-tyrosine
non-protein amino acids
bioherbicide
phenylalanine.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P20026
Abstract ID:808


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