PROMISING EPIPHYTIC ANTAGONISTIC PSEUDOMONAS STRAINS IN THE BIOCONTROL OF PSEUDOMONAS SYRINGAE. PROMISING EPIPHYTIC ANTAGONISTIC PSEUDOMONAS STRAINS FROM THE CITRUS PHYLLOSPHERE IN THE BIOCONTROL OF PSEUDOMONAS SYRINGAE

In vitro analysis of the antagonistic activity of fifty-four native epiphytic bacterial isolates from the Citrus phyllosphere towards pathogenic Pss resulted in a selection of eight potential biocontrol strains according to their various antagonistic potentials. Based on analysis of the (partial) 16S rRNA gene sequence and the rpoD housekeeping gene, five isolates were presumptively identified as Pseudomonas. atacamensis (strains Y28, Y58 and Y128), P. cremoris (strain Y40), and P. lactis (strain Y21). In vivo test of these antagonistic strains showed no pathogenicity towards plant tissues. Three strains (Y28, Y128 and Y21) exhibited considerable inhibitory activities and significantly reduced disease severity in five Citrus cultivars (Cassar, Eurêka, Maltaise, Washington Navel and Pomelo) on shoots, leaves and fruits.