The Influences of Epicuticular Wax Disruption and Cutinase Resistance on Penetration of Tomatoes by Colletotrichum gloeosporioides

Abstract

AbstractConidia of Colletotrichum gloeosporioides germinated on green and ripe tomato fruit with intact epicuticular wax, and formed penetration pegs below melanized appressoria. If the delicate layer of epicuticular wax was distupted by abrasion or removed by solvents before inoculation, apparent increased diffusion of fruit substances into the inoculum stimulated fungal growth, hyphal anastomosis and the production of penetration pegs from hyaline appressoria. This was followed by cutlcle erosion centred on the penetration pegs in green fruit allowing sec‐ondary growth of infection hyphae. Due to the development of cutinase resistance when the cuticle became yellow at ripening, no cuticle erosion occurred at penetrations on ripe fruit Since cuticle erosion followed penetration of the cutinase‐susceptible cuticle and since penetration peg formation was not hindered by the cutinase cuticle, the process of primary penetration is regarded as mechanical.