Isolation and Characterization of Factors in Sweet Potato Root Which Agglutinate Germinated Spores of Ceratocystis fimbriata, Black Rot Fungus

A factor which agglutinates the germinated spores of Ceratocystis fimbriata was isolated from the sweet potato root. The factor is a glycoprotein with a molecular weight of 1.6 x 10(6) daltons and required divalent cations such as Ca(2+), Mn(2+), Ni(2+), and Mg(2+) for activity. The activity of the factor was pH-dependent. The factor also agglutinated rabbit erythrocytes and is classified as a phytohemagglutinin or lectin. The factor agglutinated germinated spores of seven strains of C. fimbriata to almost the same degree. The factor showed differential agglutinating activity toward the strains in the presence of unidentified low molecular weight factor(s) in the sweet potato root. These results support our earlier suggestion that the spore-agglutinating factors in host plants function as the determinants of specificity in some host-parasite interactions.