Dr. Mervat Gameel Hassan :: Publications:

ABSTRACT Antibiotics have been used for the control of plant pathogenic bacteria and it has become a problem in pathosystems. The current study aimed to detection plasmid curing in species of the genus Xathomonas antibiotic resistance isolated from citrus, almonds and beans. Methods: Common bacteria blight disease in citrus , almond and beans were detected by external symptoms and DASELISA .The casual against was detected and isolated on selected media by morphological and biochemical characteristics of the colonies, Indirect immunofluorescence assay, bioassay of leaf detached leaves and Hgene by PCR .The isolated bacteria were tested antibiotic sensitivity. Results: Typical symptoms of common blight disease Xanthomonas sp on citrus, almond and beans that, necrotic spots surrounded by chlorotic haloes, sunken and corky lesions with oozing gum. Bright yellow spots on the underside of leaves, followed by erumpent brownish lesions. Symptoms were recorded at late summer through to autumn 2017. The canker, chlorotic haloes and halo blight spots gave positive serological reaction with polyclonal antibodies specific Xanthomonas sp by DASELISA . Xanthomonas sp was isolated on YPGA medium and yellow pigment colonies from naturally infected citrus, almond and beans leaves. Xanthomonas sp isolates were identified which showed some differences of physiological and biochemical properties. Xanthomonas isolates inoculation of intact .immature leaves of Nicotiana tabacum cv samson showed 65–75% to fully expanded were preferred and the lesions develop 15–20 days. Three Xanthomonas sp isolates gave positive serological reaction with polyclonal antibodies specific Xanthomonas sp by DAS-ELISA. The Hgene sequence in the genome of Xanthomonas spp isolates suggested the original assignment of this isolates to the species X.citri, X.arboricola and X. campestris based on Hgene sequence X.campestris pv. campestris str. ATCC 33913. Phylogenetically sequence comparison confirmed that Xanthomonas spp isolates closest Hgene genetic homologues all belong to X. citri subsp. citri, X. arboricola and X. campestris pv. phaseoli. Antibiotics sensitivity of Xanthomonas sp isolates showed resistance against Penicillin G, Streptomycin and more resistance against, Sulphadiazole and Tetracycline. On the contrary Xanthomonas isolates after plasmids curing treatment showed sensitivity where formed inhibition zone with different area to Penicillin G, Streptomycin, Sulphadiazole and Tetracycline.