BIOLOGICAL CONTROL OF FUNGAL PLANT PATHOGENS: STABLE INHERTIANCE OF HETEROLOGOUS ANTIBIOTIC BIOSYNTHETIC GENES IN A ROOT-COLONIZING PSEUDOMONAD.

BACTERIAL STRAINS THAT CONTROL FUNGAL PLANT PATHOGENS OFFER A BIOLOGICAL ALTERNATIVE TO THE CHEMICAL TREATMENTS NOW IN USE. THE UTILITY OF BACTERIAL INOCULANTS HAS BEEN DEMONSTRATED IN THE GLASSHOUSE UNDER CONTROLLED CONDITIONS; HOWEVER, THEIR POTENTIAL HAS YET TO BE REALIZED UNDER FIELD CONDITIONS. THIS IS DUE, IN PART, TO THE INABILITY OF THE INOCULUM STRAINS TO ESTABLISH THEMSELVES WELL ON ROOT SURFACES. THE PROPOSE'S APPROACH TO THE DEVELOPMENT OF A COMMERCIALLY VIABLE BIOLOGICAL CONTROL AGENT IS TO TRANSFER THE GENES ENCODING AN ANTIFUNGAL SUBSTANCE TO A STRAIN THAT PROLIFERATES IN THE RHIZOSPHER UNDER FIELD CONDITIONS. STABLE INHERITANCE OF HETEROLOGOUS GENES BY THE ROOT-COLONIZING RECIPIENT IS ESSENTIAL. IN THIS RESEARCH THEY PROPOSE TO TEST A NOVEL PLASMID SYSTEM AND ALSO CHROMOSOMAL INTEGRATION AS MEANS TO ENSURE STABLE INHERITANCE. GENES WILL BE TRANSFERRED THAT CODE FOR A CHARACTERIZED SIDEROPHORE-LIKE FUNGAL ANTAGONIST MOLECULE PRODUCED BY PSEUDOMONAS FLUORESCENS STRAIN NZ130; THEY WILL BE INTRODUCED INTO THE AGGRESSIVE ROOT COLONIZING STRAIN OF P. PUTIDA MK280. THEY WILL ASSESS THE RESULTING RECOMBINANT ORGANISM'S ABILITY TO CONFER PYTHIUM DISEASE RESISTANCE TO COTTON SEEDLINGS IN A MODEL SOIL ASSAY SYSTEM, AND THE FEASIBILITY OF ITS DEVELOPMENT AS A COMMERCIAL BIOLOGICAL CONTROL AGENT.