PARTIAL CHARACTERIZATION OF CYTOSOLIC SUPEROXIDE-DISMUTASE ACTIVITY IN THE INTERACTION OF MELOIDOGYNE-INCOGNITA WITH 2 CULTIVARS OF GLYCINE-MAX

The closely related soybean (Glycine max) cultivars Centennial and Pic kett 71 were confirmed to be resistant and susceptible, respectively, to the root-knot nematode Meloidogyne incognita. Increases in superoxi de dismutase (SOD) activity were detected in roots of both soybean cul tivars 48 hours following inoculation. Superoxide dismutase activity i ncreased in roots of the susceptible cultivar overall, but declined af ter 96 hours in roots of the resistant cultivar. The isoelectric point s of SOD isolated from preparasitic and parasitic developmental stages of the nematode appeared to differ. The SOD activity increased dramat ically as nematodes matured and enlarged. Plant and nematode SOD were present as ca. 40-kDa cuprozinc dimers. Initial increases in SOD activ ity in infected tissue appeared to involve nematode regulation of plan t gene expression. However, as the nematode enlarged, SOD activity cou ld be detected within the female body only.