Cryptococcus laurentii controls gray mold of cherry tomato fruit via modulation of ethylene-associated immune responses

This research aimed to investigate the roles of phytohormone ethylene in cherry tomato fruit immune response against gray mold caused by Botrytis cinerea. Pretreatment with antagonistic yeast Cryptococcus laurentii resulted in a significantly decreased disease incidence of B. cinerea infection, and accompanied by a burst of ethylene production in the whole fruit. Blocking the ethylene perception by adding 1-MCP (5 mu L L-1 or greater) remarkably weaken the protection ability of fruit itself and suppressed the C. laurentii-stimulated host immune response. 5 mu L L-1 1-MCP prefumigation decreased the expression of ethylene biosynthesis and perception related genes SlACO1, SlACS2, SlERF1, SlPti5 and SlMPK3, and ethylene production in C. laurentii treated fruit. Consequently, the expressions of SlCHI9, SlGlub, SlPAL3, SlPR1 and SlPR5 up-regulated by the yeast were all impaired to different degrees by the 1-MCP prefumigation. These findings demonstrate that ethylene contributes to fruit immunity and C. laurentii-mediated immune responses of cherry tomato.