BACTERIAL LEAF SPOT DISEASE OF PEPPER CAUSED BY Xanthomonas axonopodis IN SAUDI ARABIA: IDENTIFICATION AND BIOCONTROL USING Streptomyces sp. In-Vitro

Xanthomonas genus causes lesions on plant leaves, sterns, and fruits. Xanthomonas campestris is considered as one of the most devastating pathogens that infects pepper and tomato worldwide. Traditionally the Xanthomonas disease are controlled by using chemicals control methods that possess numerous demerits. There is a need to develop an effective and safe biocontrol strategies to control these diseases. The present work was aimed to isolate and identify Xanthomonas sp. from infected pepper plants and to develop a suitable biocontrol agent. In the present study we report four new isolates of X. axonopodis from infected pepper plants. Based on 16S rDNA homology, these isolates were identified as X. axonopodis QXP1, X. axonopodis QXP2, X. axonopodis QXP3, and X. axonopodis QXP5. These isolates were able to cause the re-infections in pepper plant Eight strains of Streptomyces sp. were tested for their biocontrol activity against Xanthomonas isolates. Streptomyces tricolor strain HM10 exhibited potent biocontrol activity against the tested pathogens. To the best of our knowledge, this is the first report regarding the isolation X axonopodis from pepper plants.