title: Grass roots chemistry: meta-tyrosine, an herbicidal nonprotein amino acid.
abstract: Fine fescue grasses displace neighboring plants by depositing large quantities of an aqueous phytotoxic root exudate in the soil rhizosphere. Via activity-guided fractionation, we have isolated and identified the nonprotein amino acid m-tyrosine as the major active component. m-Tyrosine is significantly more phytotoxic than its structural isomers o- and p-tyrosine. We show that m-tyrosine exposure results in growth inhibition for a wide range of plant species and propose that the release of this nonprotein amino acid interferes with root development of competing plants. Acid hydrolysis of total root protein from Arabidopsis thaliana showed incorporation of m-tyrosine, suggesting this as a possible mechanism of phytotoxicity. m-Tyrosine inhibition of A. thaliana root growth is counteracted by exogenous addition of protein amino acids, with phenylalanine having the most significant effect. The discovery of m-tyrosine, as well as a further understanding of its mode(s) of action, could lead to the development of biorational approaches to weed control.
authors.affiliation: Department of Horticulture, and Boyce Thompson Institute, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Cécile
authors.initials: C
authors.lastname: Bertin
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Weston
authors.forename: Tengfang
authors.initials: T
authors.lastname: Huang
authors.forename: Georg
authors.initials: G
authors.lastname: Jander
authors.forename: Thomas
authors.initials: T
authors.lastname: Owens
authors.forename: Jerrold
authors.initials: J
authors.lastname: Meinwald
authors.forename: Frank C
authors.initials: FC
authors.lastname: Schroeder
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000633:toxicity*; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development; D005591:Chemical Fractionation; D006540:Herbicides / Q000633:toxicity*; D018545:Lactuca / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry* / Q000187:drug effects* / Q000254:growth & development; D006109:Poaceae / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry / Q000633:toxicity*
chemical_list: D000596:Amino Acids; D006540:Herbicides; D010936:Plant Extracts; D014443:Tyrosine; C015566:3-tyrosine