Abstract
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.
Highlights
Seed production has been moved to semi-arid regions to escape seed-borne pathogens
The species-specific PCR assays, biochemical and serological analyses were used to identify the Xanthomonas species associated with bacterial leaf spot of tomato as diagnostic protocols for this disease (Manjula et al, 2017; Roach et al, 2018; Vancheva et al, 2018).the present study was conducted to achieve the following objectives: to isolate the seed-borne bacterial pathogens from solanaceous plants collected from different locations in Egypt, to identify and characterize the isolated bacteria through cultural, biochemical tests and fatty acid profiling,as well as, molecular techniques through 16S rRNA gene sequences
Different bacterial colonies were observed on glycerol agar, nutrient agar, yeast extract dextrose-CaCo3 (YDC), as well as, semi selective media, PA20, King's B and Tween B (Table 1)
Summary
Seed production has been moved to semi-arid regions to escape seed-borne pathogens. Seed-borne bacterial diseases continue to be problematic and cause significant economic losses worldwide. The species-specific PCR assays, biochemical and serological analyses were used to identify the Xanthomonas species associated with bacterial leaf spot of tomato as diagnostic protocols for this disease (Manjula et al, 2017; Roach et al, 2018; Vancheva et al, 2018).the present study was conducted to achieve the following objectives: to isolate the seed-borne bacterial pathogens from solanaceous plants collected from different locations in Egypt, to identify and characterize the isolated bacteria through cultural, biochemical tests and fatty acid profiling ,as well as, molecular techniques through 16S rRNA gene sequences. Seeds of different varieties of some selected vegetable crops and weeds which belonging to family Solanaceae were collected as following: 6 varieties of tomato seeds (Solanum esculentum) namely Castle Rock, Super strain B, Peto 86, Super Jakal, Gs 12 and local variety were purchased from local markets at Alexandria Governorate.
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