title: Stable Isotope Resolved Metabolomics Reveals the Role of Anabolic and Catabolic Processes in Glyphosate-Induced Amino Acid Accumulation in Amaranthus palmeri Biotypes.
abstract: Biotic and abiotic stressors often result in the buildup of amino acid pools in plants, which serve as potential stress mitigators. However, the role of anabolic (de novo amino acid synthesis) versus catabolic (proteolytic) processes in contributing to free amino acid pools is less understood. Using stable isotope-resolved metabolomics (SIRM), we measured the de novo amino acid synthesis in glyphosate susceptible (S-) and resistant (R-) Amaranthus palmeri biotypes. In the S-biotype, glyphosate treatment at 0.4 kg ae/ha resulted in an increase in total amino acids, a proportional increase in both (14)N and (15)N amino acids, and a decrease in soluble proteins. This indicates a potential increase in de novo amino acid synthesis, coupled with a lower protein synthesis and a higher protein catabolism following glyphosate treatment in the S-biotype. Furthermore, the ratio of glutamine/glutamic acid (Gln/Glu) in the glyphosate-treated S- and R-biotypes indicated that the initial assimilation of inorganic nitrogen to organic forms is less affected by glyphosate. However, amino acid biosynthesis downstream of glutamine is disproportionately disrupted in the glyphosate treated S-biotype. It is thus concluded that the herbicide-induced amino acid abundance in the S-biotype is contributed by both protein catabolism and de novo synthesis of amino acids such as glutamine and asparagine.
authors.affiliation: Department of Plant & Environmental Sciences, Clemson University , Clemson, South Carolina 29634, United States.
authors.forename: Amith
authors.initials: A
authors.lastname: Maroli
authors.affiliation: Crop Production Systems Research Unit, U.S. Department of Agriculture , Stoneville, Mississippi 38776, United States.
authors.forename: Vijay
authors.initials: V
authors.lastname: Nandula
authors.affiliation: Natural Products Utilization Research Unit, Agricultural Research Service, U.S. Department of Agriculture , Oxford, Mississippi 38677, United States.
authors.forename: Stephen
authors.initials: S
authors.lastname: Duke
authors.affiliation: Department of Plant & Environmental Sciences, Clemson University , Clemson, South Carolina 29634, United States.
authors.forename: Nishanth
authors.initials: N
authors.lastname: Tharayil
mesh_terms: D027721:Amaranthus / Q000737:chemistry* / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D055432:Metabolomics; D009587:Nitrogen Isotopes / Q000032:analysis; D000097797:Glyphosate
chemical_list: D000596:Amino Acids; D005998:Glycine; D006540:Herbicides; D009587:Nitrogen Isotopes; D000097797:Glyphosate
keywords: 15N isotopologue; Amaranthus palmeri; LC-MS/MS; amino acid accumulation; anabolic and catabolic processes; de novo biosynthesis