The tissue and cellular location of a major cross-reactive antigen shared by cotton and soil-borne fungal parasites

Abstract

A major cross-reactive antigenic substance (CRA), common to cotton ( Gossypium hirsutum ) and certain fungal parasites of cotton roots, was isolated and purified to homogeneity from conidial cultures of Fusarium oxysporum f.sp. vasiufectum (F.o.v,). Agar gel double-diffusion tests indicated the prcscncc of CRA not only in F.o.v. and in cotton roots and seed but also in Thielaviopsis bosicola . Indirect staisung of antibodies using fluorescein isothiocyanate (FITC) indicated that in cross-sections of roots, cut near or just below the root hair zone, the CPA was concentrated mainiy around xylem elements, the endodernais and epidermal cells and was present throughout the cortex tissue. Protoplasts prepared from cross-sections of young cotton roots also contained the CPA which was concentrated in the region of the plasmalemma. Treatment of conidia and mycelia of F.o.v. with antiserum to cotton and using indirect staining with FITC indicated that the CRA was mainly present in hyphal tips and in patch-like aseas on conidia. The possible role of CRA in basic compatibility of host and parasite is discussed.