PLANT PATHOGENS, MOST OF THEM FUNGI, DESTROY AT LEAST 10% OF THE GLOBAL FOOD SUPPLY ANNUALLY AND REPRESENT AN INCREASING THREAT TO WORLD FOOD SECURITY. FUNGAL PATHOGENS SECRETE DIVERSE ARRAYS OF "EFFECTOR" PROTEINS INTO LIVING HOST TISSUES, WHERE THEY INDUCE ACCESSIBILITY OF THE PLANT CELLS BY SUPPRESSING RESISTANCE AND PROMOTING SUSCEPTIBILITY. THERE IS CLEAR EVIDENCE SUGGESTING A VARIETY OF IMPORTANT ROLES FOR THESE EFFECTORS IN MULTIPLE ASPECTS OF PATHOGENESIS. ALTHOUGH WE HAVE MADE SIGNIFICANT PROGRESS ON IDENTIFYING THE MODES OF ACTION OF INDIVIDUAL EFFECTORS, AND HAVE CATALOGUED THE EFFECTOR REPERTOIRES OF MANY PATHOGENIC FUNGI, WE STILL KNOW VERY LITTLE ABOUT THE UNDERLYING MECHANISMS THAT REGULATE THE PRODUCTION AND SECRETION OF EFFECTORS IN PLANTA. AND YET, GIVEN THAT INDIVIDUAL EFFECTORS ARE OFTEN FUNCTIONALLY REDUNDANT AND POORLY CONSERVED ACROSS TAXA, UNDERSTANDING THE SECRETION MECHANISM OF EFFECTORS OFFERS OUR BEST HOPE FOR BROAD-SPECTRUM CONTROL OF THESE DEVASTATING FUNGAL PATHOGENS. THE PROPOSED RESEARCH IS TO INVESTIGATE THE HYPOTHESIS THAT THE SECRETORY MACHINERY OF PATHOGENIC FUNGI HAS AN IMPORTANT, PREVIOUSLY UNKNOWN, REGUATORY ROLE IN EFFECTOR SECRETION IN PLANTA. OUR PREVIOUS OBSERVATIONS HAVE SUGGESTED A MECHANISM FOR THIS REGULATION THAT INVOLVES A HIGHLY CONSERVED COMPONENT OF THE SIGNAL PEPTIDASE COMPLEX THAT IS THE GATEKEEPER FOR PROTEIN TRANSPORT AND SECRETION. OUR HYPOTHESIS IS THAT THIS COMPONENT OF THE COMPLEX IS ITSELF REGULATED BY A STRESS RESPONSE THAT IS TRIGGERED BY SIGNALS FROM THE PLANT HOST, AND THAT, WHEN ACTIVATED, IT FACILITATES THE RAPID PRODUCTION AND SECRETION OF CRITICAL EFFECTORS DURING EARLY PATHOGENICITY. IF THE HYPOTHESIS IS SUPPORTED, IT MAY LEAD TO A NEW APPROACH FOR BROAD-SPECTRUM CONTROL OF FUNGAL PATHOGENS.