Fatty acids, aldehydes and alcohols as attractants for zoospores of Phytophthora palmivora

Abstract

ZOOSPORES of the important plant pathogenic fungi Pythium and Phytophthora are attracted to plant roots and to exudates and extracts from roots¹. Attraction (positive chemotaxis) to amino acids^2,3 which occur in root exudates, and ethanol⁴, which will be produced by roots in waterlogged soils, has been demonstrated, but no substance has been found which by itself is as powerful an attractant as root exudate. The attractiveness of root exudates must therefore be explained by additive or synergistic effects between the known attractants, or by powerful attractants which have hitherto escaped detection, or both. There is evidence for additive and synergistic effects⁵, but the fractionation of root exudates has not so far yielded evidence of additional chemotactic factors. We report here the existence of further attractants for fungal zoospores, and consider the possibility that they may be of significance in chemotaxis to plant roots.