BIOCHEMICAL AND SEROLOGICAL COMPARISON OF LECTINS FROM DIFFERENT ANASTOMOSIS GROUPS OF RHIZOCTONIA-SOLANI

Twenty five isolates of different anastomosis groups of Rhizoctonia solani and a few related species were checked for the presence of lectins. All isolates of Rhizoctonia solani as well as Aquathanatephorus pendulus, Rhizoctonia crocorum and Athelia rolfsii contained lectins which comprised between 0.2 and 35% of the total protein. The lectins were isolated by affinity chromatography and analyzed by ion-exchange chromatography which revealed that some isolates contained different isolectins. SDS-PAGE and gel filtration indicated that the molecular weights of the monomer polypeptides varied between 11 and 20 kDa whereas that of the native lectins ranged from 28 to 44 kDa. Although the lectins are most likely dimers, one R. solani lectin behaves as a monomer. Serological relationships between the lectins were investigated by double immunodiffusion assays and quantified by ELISAs. Thereby it became evident that lectins from R. solani AG-1 isolates and those from A. pendulus are closely related serologically by reaction with an antiserum against a lectin of an isolate of AG-1. Similarly all AG-4 isolates of R. solani appear to be closely related to each other; they are all recognized by the antiserum to a lectin from R. solani AG-4 but not by antiserum to a lectin from R. solani AG-1. The use of the lectins in ELISAs to determine the AG of R. solani isolates is discussed.