TARGETED SECRETION OF CUTINASE IN FUSARIUM-SOLANI F-SP PISI AND COLLETOTRICHUM-GLOEOSPORIOIDES

Immunofluorescence studies of cutinase secretion by phytopathogenic fungi Fusarium solani f. sp. pisi and Colletotrichum gloeosporioides were made to determine targeting of the enzyme in germinating spores. Our results indicate that the secretion of cutinase was directed towards the region that penetrates the host. In F. s. pisi, which penetrates plant tissue without appressorium formation, cutinase was targeted to the growing tip of germinating spores. In C. gloeosporioides, cutinase secretion was directed to the infection peg that arises from the appressorium. Monensin, the carboxylic ionophore, inhibited secretion of cutinase and caused intracellular accumulation of cutinase in F. s. pisi. Subcellular fractionation of monensin-treated cells indicated involvement of the Golgi in the secretion and targeting of cutinase by germinating spores of F. s. pisi.