Title

Signaling by glutamate dehydrogenase in response to pesticide treatment and nitrogen fertilization of peanut (Arachis hypogaea L.)

Document Type

Article

Publication Title

Journal of Agricultural and Food Chemistry

Abstract

The responses of glutamate dehydrogenase (GDH) to NH4+ and herbicides offer a new approach for probing the effects of NH4+-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 NH4Cl 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 NH4Cl-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 NH4+ 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 NH4+, at least 70% of the pesticide signal was overridden by NH4+ 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.

First Page

3332

Last Page

3344

DOI

10.1021/jf9805303

Publication Date

1-1-1999

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