Comparative analysis of proteins of Uromyces phaseoli var. typica, U. phaseoli var. vignae, and U. viciae-fabae: polypeptide mapping by two-dimensional electrophoresis

Abstract

Proteins were extracted from urediospores of the bean rust fungus (Uromyces phaseoli var. typica: two isolates), of the cowpea rust fungus (U. phaseoli var. vignae; two isolates), and of the faba bean rust fungus (U. viciae-fabae; one isolate) and separated by two-dimensional isoelectric focusing – polyacrylamide gel electrophoresis under denaturing conditions. The two isolates of the cowpea rust fungus had identical polypeptide patterns; the two isolates of the bean rust fungus differed by 19 polypeptides. The polypeptide patterns of the bean rust, cowpea rust, and faba bean rust fungi differed markedly from each other. There were 277 polypeptides detected in extracts of the faba bean rust fungus, while more than 335 polypeptides were detected in extracts of each isolate of the other two fungi. While U. phaseoli var. typica and U. phaseoli var. vignae shared 183 polypeptides, U. viciae-fabae had only 149 and 146 polypeptides, respectively, in common with the other two rust fungi. This is consistent with the view that the two varieties of U. phaseoli are more closely related to each other than to U. viciae-fabae. However, when all detected polypeptides were compared, the differences between the two varieties were as extensive as those found between species. It is suggested, therefore, that the designation, by some mycologists of the cowpea rust fungus as a separate species, U. vignae, is correct.