title: Signaling by glutamate dehydrogenase in response to pesticide treatment and nitrogen fertilization of peanut (Arachis hypogaea L.).
abstract: The responses of glutamate dehydrogenase (GDH) to NH(4)(+) and herbicides offer a new approach for probing the effects of NH(4)(+)-pesticide interactions at the whole-plant level. Although pesticides and fertilizers have greatly enhanced food production, their combined biochemical effects are not known in detail. Peanut plants were treated with different rates of Basagran (3-(1-methylethyl)-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide), Bravo 720 (tetrachloroiso-phthalonitrile), and Sevin XLR Plus (1-naphthyl N-methylcarbamate), with and without 25 mM NH(4)Cl fertilization. Isoelectric focusing, followed by native 7.5% polyacrylamide gel electrophoresis (PAGE) fractionated the peanut seed GDH fully to its isoenzyme population patterns. The pesticide treatments induced positive skewing of the GDH isoenzymes, but NH(4)Cl-pesticide cotreatments induced a negatively skewed distribution. Basagran, Sevin, and Bravo increased the amination activities of GDH from 30.0 +/- 2.8 units in the control assay to 479.0 +/- 20.7, 63.0 +/- 5.8, and 35.2 +/- 2.2 units, respectively, therefore indicating a direct GDH-pesticide interaction. Neither the NH(4)(+) nor the pesticides increased the peanut seed protein yields above the threshold of 3.8 +/- 0.7 g per pot. But in the GDH combination of the signals from a pesticide and NH(4)(+), at least 70% of the pesticide signal was overridden by NH(4)(+) with concomitant increases in peanut seed protein yields to 7.0 +/- 1.8 g per pot. Basagran, Sevin, and Bravo possess different pesticidal properties, but their effects on GDH activity were related in the decreasing order of their nucleophilicity, viz. Basagran > Sevin > Bravo.
authors.affiliation: CARC, Prairie View A&M University, Texas 77446, USA. Godson_Osuji@PVAMU.edu
authors.forename: G O
authors.initials: GO
authors.lastname: Osuji
authors.forename: C
authors.initials: C
authors.lastname: Braithwaite
mesh_terms: D010367:Arachis / Q000187:drug effects / Q000201:enzymology*; D001581:Benzothiadiazines / Q000494:pharmacology; D012721:Carbaryl / Q000494:pharmacology; D005308:Fertilizers; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D006540:Herbicides / Q000494:pharmacology; D007700:Kinetics; D009584:Nitrogen / Q000494:pharmacology*; D010575:Pesticides / Q000494:pharmacology*; D010940:Plant Proteins / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology
chemical_list: D001581:Benzothiadiazines; D005308:Fertilizers; D006540:Herbicides; D010575:Pesticides; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D005969:Glutamate Dehydrogenase; D009584:Nitrogen; C002003:bentazone; D012721:Carbaryl