GENETIC MODIFICATIONS FOR INCREASING BIOCONTROL ACTIVITIES OF ENTEROBACTER AGGLOMERANS AGAINST SCLEROTINIA SCLEROTIORUM

摘要

Enterobacter agglomerans strain IC1270, a broad range antagonist of plant pathogenic fungi, produces a series of chitinolytic enzymes and pyrrolnitrin. Four derivatives of strain IC 1270, each carrying one of the genes of Pseudomonas fluorescens encoding the two-component global regulation system (gacA, apdA) and the transcription sigma factors (rpoS, rpoD) were constructed. It was shown that chitinolytic activity of derivatives carrying gacA or rpoD loci is higher in comparison with the parental strain. Both of these derivatives more efficiently suppressed the fungal pathogen Sclerotinia sclerotiorum in vitro and protected rapeseed against this fungus under greenhouse conditions. Strain IC1270 does not produce N-hexanoyl-L-homoserine lactone (HHL)quorum-sensing signal molecules; however, its chitinolytic and antifungal activities can be enhanced by treatment with exogenous HHL. The data suggest that the accessing of heterologous regulatory genes and interspecies cell-to-cell talking via quorum sensing mechanism may contribute to successful competition with plant pathogens under natural environmental conditions.