DETECTION OF CROSS-REACTIVE ANTIGENS SHARED BY FUSARIUM-OXYSPORUM ANDGLYCINE-MAX BY INDIRECT ELISA AND THEIR CELLULAR LOCATION IN ROOT TISSUES

Pathogenicity test of Fusarium oxysporum on ten cultivars of soybean r evealed Soymax and Punjab-l to be most resistant while JS-2 and UPSM-1 9 were most susceptible. Antigens were prepared from the roots of all the ten varieties of soybean and the mycelium of F. oxysporum. Polyclo nal antisera were raised against the mycelial suspension of F. oxyspor um and the Toot antigen of the susceptible cultivar UPSM-19. Cross rea ctive antigens shared by the host and the pathogen were detected first by immunodiffusion. The immunoglobulin fraction of the antiserum was purified by ammonium sulfate precipitation and DEAE-Sephadex column ch romatography. The immunoglobulin fractions were used for detection of cross-reactive antigens by enzyme-linked immunosorbent assay. In enzym e-linked immunosorbent assay, antigens of susceptible cultivars showed higher absorbance values when tested against the purified anti-F, oxy sporum antiserum. Antiserum produced against UPSM-19 showed cross-reac tivity with the antigens of other cultivars. Indirect staining of anti bodies using fluorescein isothiocyanate indicated that in cross-sectio ns of roots of susceptible cultivar (UPSM-19) cross-reactive antigens were concentrated around xylem elements, endodermis and epidermal cell s, while in the resistant variety, fluorescence was concentrated mainl y around epidermal cells and distributed in the cortical tissues. CRAs were also present in microconidia, macroconidia and chlamydospores of the fungus.