THE HUMAN POPULATION IS PROJECTED TO REACH 9.7 BILLION BY 2050. THE LOOMING CHALLENGE OF FEEDING THE RAPIDLY GROWING POPULATION IS THREATENED BY CROP LOSSES FROM PLANT DISEASES.PHYTOPHTHORA ARE FILAMENTOUS EUKARYOTIC PATHOGENS THAT EXERT MAJOR THREATS TO FOOD SAFETY AND HUMAN WELLNESS. HUNDREDS OF BILLIONS OF DOLLARS ARE LOST EACH YEAR DUE TO DESTRUCTIVE CROP DISEASES CAUSED BY PHYTOPHTHORA SPECIES. THE MOST NOTORIOUS IS THE POTATO LATE BLIGHT PATHOGEN PHYTOPHTHORA INFESTANS, WHICHWAS THE CULPRIT OF THE IRISH FAMINE IN THE NINETEENTH CENTURY AND REMAINS A SERIOUS PROBLEM WORLDWIDE. OTHER IMPORTANT PHYTOPHTHORA DISEASES INCLUDE THE SUDDEN OAK DEATH THAT HAS KILLED MILLIONS OF FOREST TREES. AS A GROUP OF PATHOGENS WITH BOTH HISTORICAL AND CURRENT IMPORTANCE, BATTLINGPHYTOPHTHORADISEASES IS AN IMPORTANT MISSION AND A MAJOR CHALLENGE IN AGRICULTURE.THE MAIN GOAL OF THIS PROJECT IS TO UNDERSTAND HOW PHYTOPHTHORA CAUSES DISEASES AND TO USE THIS KNOWLEDGE TO IDENTIFY PLANT GENESTHAT COULD CONFER SUSTAINABLE DISEASE RESISTANCE. CUTTING-EDGE MOLECULAR BIOLOGY, BIOCHEMISTRY AND GENETICS APPROACHES WILL BE EMPLOYED TO INVESTIGATE THE MOLECULAR MECHANISMS UNDERLYING THE VIRULENCE CONTRIBUTION OF A CONSERVED STRUCTURAL MODULE INPHYTOPHTHORA, WHICH MAY SERVE AS A BASIC BUILDING BLOCK OF A LARGE NUMBER OF VIRULENCE PROTEINS. A COLLECTION OF WILD POTATO SPECIES WILL ALSO BE SCREENED TO IDENTIFY RESISTANCE GENES THAT CAN TRIGGER IMMUNITY UPON RECOGNITION OFTHIS BASIC STRUCTURAL MODULE OF THE PATHOGEN.THE OUTCOME OF THIS PROJECT WILL MAKE MAJOR ADVANCEMENT IN THE FUNDAMENTAL UNDERSTANDING OF THE DESTRUCTIVEPHYTOPHTHORA DISEASES. THE RESISTANCE GENES IDENTIFIED FROM WILD POTATO ACCESSIONS MAY BE INCORPORATED INTO ELITE VARIETIES IN ORDER TO CONFER RESISTANCE TO LATE BLIGHT. THESE GENES COULD ALSO BE INTRODUCED IN OTHER IMPORTANT CROPS TO CONFER SUSTAINABLE RESISTANCE TO A BROAD VARIETY OF PHYTOPHTHORA SPECIES.