In vitro Antimicrobial Assay of Actinomycetes in Rice AgainstXanthomonas oryzae pv. oryzicola and as Potential Plant Growth Promoter

ABSTRACT

ABSTRACT The aim of this work was to invitro assay the antimicrobial activity of actinomycetes in rice against Xanthomonas oryzae pv. oryzicola and as potential plant growth promoter. A total of 92 actinomycete strains were isolated from different rice plant components and field locations. Of these, only 21.74% showed antagonistic activity against the Xoc pathogen. Molecular identification via 16s rRNA amplification revealed that 60% of the active antagonistic strains belonged to the genus Streptomyces. Isolates that demonstrated the highest antagonistic activity were also able to produce hydrolytic enzymes and plant growth-promoting hormones. Combination of preliminary screening based on in vitro antagonistic, hydrolytic enzyme and plant growth hormone activity facilitated the best selection of actinomycete candidates as evidenced by strains classification using cluster analysis (Ward's Method). Results from the preliminary screening showed that actinomycetes, especially Streptomycetes, could offer a promising source for both biocontrol and plant growth-promotion agents against BLS disease in rice.