Chemotaxis of Zoospores for Root Exudates.

A chemotactic response of the zoospores of a soil-inhabiting plant pathogenic fungus, Phytophthora cinnamomi, for roots of avocado seedlings was observed. The chemotaxis of the zoospores and chemotropy of their germ tubes were directly related to infection and disease production. Indications were obtained of specificity of the pathogen-attracting root exudate, and interesting implications are evident with regard to mechanisms of invasion and pathogenicity, and to disease resistance.