PATHOLOGICAL, BIOCHEMICAL AND MOLECULAR CHARACTERIZATION OF THE SEED-BORNE BACTERIA "PANTOEA SPP., XANTHOMONAS SPP. AND PSEUDOMONAS SPP." FROM SOLANACEOUS PLANTS IN EGYPT
Keywords:seed borne bacteria, solanaceae, fatty acids, 16S rRNA, PA20
The seed-borne bacterial diseases of family solanaceae cause significant economic losses worldwide. In the present study, fourteen bacterial isolates were recovered from seeds of different varieties of tomato, eggplant, black nightshade and tobacco. The seed samples were collected from different locations in Egypt. Isolated bacteria were identified based on morphological, physiological and biochemical tests as well as colonial morphology aspects on the differential medium, yeast extract dextrose calcium carbonate (YDC) besides the selective media (PA 20, King's B and Tween B). Pathogenicity of the isolated bacteria was assessed for causing graywall, bacterial speck and bacterial spot symptoms on tomato seedlings. Disease symptoms were recognized on leaves and stems of the inoculated seedlings. Re-isolation from collected seeds of the inoculated tomato plants was performed. Results indicated that Pantoea spp. was an endophytic bacteria, Pseudomonas spp. was an epiphytic bacteria, while Xanthomonas spp. was both epiphytic and endophytic bacteria. Furthermore, cellular fatty acids composition were identified and quantified to give a profile for tested bacterial isolates. Moreover, the bacterial isolates were identified at the molecular level via PCR reactions utilizing the 16S rRNA gene. Partial DNA sequences were analyzed using BLAST tool revealed that the inferred 16S rRNA partial sequences of the 7 isolates showed similarity to Pantoea ananatis (3 isolates), Pseudomonas syringae pv. tomato (2 isolates) and Xanthomonas vesicatoria (2 isolates). To the best of our knowledge the bacterium associated with the graywall seems to be first report of P. ananatis isolated from tomato fruits and black nightshade seeds in Egypt.
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