Aggressiveness of Conidiobolus obscurus against the pea aphid : IV. Electrophoretic and immunoelectrophoretic characterization of aggressive strains

A combination of electrophoretic and serological techniques was utilized to differentiate among twelve Conidiobolus obscurus isolates which varied in their ability to infect the pea aphid, Acyrthosiphon pisum. Electrophoresis of mycelial homogenates in polyacrylamide slab gels in conjunction with various histochemical staining systems produced isozyme patterns which clustered C. obscurus into three major groups. The aggressive strains (A +) were contained within two groups whereas the nonaggressive (A −) strains were all clustered in one group. Immunoelectrophoresis of anti-A + sera adsorbed with A − antigens produced precipitin lines only with the A + antigens, not with the A − antigens. Similar results were obtained with anti-A − sera adsorbed with A + antigens tested against A − antigens. The groups of A + and A − strains tested possessed specific antigenic fractions which were common to all strains inside a group and were therefore likely to be related to aggressiveness.