PHYTOALEXIN ACCUMULATION IN GROUNDNUTS IN RESPONSE TO WOUNDING

Imbibed cotyledons of groundnut, Arachis hypogaea, accumulated the phytoalexins resveratrol, 4-(3-methyl-but-l-enyl)-3,5,4' trihydroxystilbene (arachidin III) and 3-isopentadienyl-4,3',5'-trihydroxystilbene (arachidin IV) in response to wounding. By 48 h after slicing cotyledons, phytoalexin amounts, in mu-M/g fresh weight, varied form 0.0-0.59 for reserveratrol, 0.02-0.98 for arachidin III and 1.11-4.39 for arachidin IV, depending on cultivar, maturity and viability of the seed. Inclusion of cycloheximide at 50-mu-g/ml or 100-mu-g/ml caused reductions in phytoalexin accumulation of up to 69% and 96%, respectively. Pegs and immature pods, when wounded by slicing, accumulated 0.0-0.14-mu-M/g fresh weight arachidin III and 0.17-0.90-mu-M/g fresh weight arachidin IV, the amounts varying according to the stage of maturity.