PEANUT GLUTAMATE-DEHYDROGENASE - A TARGET SITE OF HERBICIDE ACTION (REPRINTED FROM PLANT NUTRITION FOR SUSTAINABLE FOOD-PRODUCTION AND ENVIRONMENT, 1997)

Germination of peanut seeds in 5 mM N-(phosphonomethyl) glycine isopro pylamide, 1, 2-dihydro-3, 6-pyridazinedione (maleic hydrazide), glypho sate, and isopropylamine solutions induced stress response reactions a nd the release of 24-100 mu mol NH4+ per 50 g of seed, with consequent differential suppression of the subunits of glutamate dehydrogenase ( GDH). Changes in the GDH isomerization suggested an interaction of the herbicides with the enzyme with consequent increases in the Michaelis constants (Km) from 7.7 mM in the control to 45.0, 50.0 and 77.0 mM N H4+ in the glyphosate, maleic hydrazide, and glyphosate isopropylamide treatments respectively.