Biocontrol properties of pseudozyma flocculosa a natural antagonist of powdery mildew fungi

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Practical application of biological control of plant pathogens presupposes a thorough understanding of the chemical, biochemical and molecular events underlying such phenomena. This challenge has been the focal point of the research activities carried out in the applicant's  laboratory over the last 16 years. In the previous installment, we have made some important strides toward elucidating key factors governing the biocontrol properties of Pseudozyma flocculosa, a natural antagonist of powdery mildew fungi. Of particular significance, we reported: 1) the structure of an unusual glycolipid accounting for the biocontrol activity of P. flocculosa; 2) the optimization of a genetic transformation system by insertional mutagenesis; 3) the development of a novel technique, reversed intron PCR, that allowed the differentiation of P. flocculosa from other related species and among geographically distinct isolates of P. flocculosa; 4) the antifungal activity of flocculosin against yeast strains of medical importance; and 5) successful expression of foreign genes in P. flocculosa including GFP. In the context of this application and on the basis of our recent progress, the objectives are: 1) to generate and characterize mutants defective for flocculosin production 2) to study and compare potential gene(s) involved in glycolipid production in P. flocculosa and U. maydis; 3) to generate GFP-mutants in both wild type (Wt) and tox- strains of P. flocculosa; 4) to conduct spatio-temporal studies to compare the ecological behavior of P. flocculosa Wt and tox- strains transformed with GFP and 5) to determine the relevance of flocculosin (and related glycolipids) as a fitness determinant in the ecology of P. flocculosa isolates. Fulfillment of these objectives will generate novel and original information with regards to: the genetic determinants that regulate the biocontrol activity of P. flocculosa against powdery mildews and other phyllosphere inhabitants; these results will have far reaching impact into the study of powdery mildew diseases in general and into the study of the genetic, chemical and ecological properties of microbial biocontrol agents, concerns of key importance for their eventual use and manipulation.