Mechanism of Electrotaxis of Zoospores of Phytopathogenic Fungi

Abstract

Plant roots generate weak electrical fields in the rhizosphere that may stimulate electrotactic swimming of zoospores of plant pathogenic fungi. Here we show that in vitro electrotaxis of zoospores of Pythium aphanidermatum was cathodic, whereas those of two other Pythium species and Phytophthora palmivora were anodic. Electrotaxis occurred in electrical fields comparable in magnitude to those generated by plant roots. Electrical fields of a physiological magnitude had little effect on the velocity of swimming but increased the turning frequency of the zoospores of P. palmitora over threefold. Reagents that affected calcium ion transport or calmodulin function had an apparent effect on electrotaxis, but most also induced premature encystment or cell lysis [...]