ABSTRACT
Tomatoes plant and seeds have been affected by bacterial contamination and early infection,
during its developmtal stage resulting plant disease cases in affected farm-lands of Delta State.
Our study investigates isolation and molecular characterisation of Xanthomonas campestris from
tomatoes plant in Oghara. Four locations in the study area were surveyed while freshly harvested
tomato and suspected bacterial leaf spot infected tomato plant samples were collected and
analyzed. Standard microbiological techniques for the isolation of bacteria were employed.
Morphological and biochemical characteristics, viz., Gram’s reaction, colonial characteristics,
pigment production, KOH test, catalase test, starch hydrolysis, acid production, and gelatin
liquefication tests, were carried out. Further confirmation tests employing molecular
characterization using the bacterial universal primer fdl rp2 which targets the 16S rRNA region
of Xanthomonas campestris pv vesicatoria as a specific primer pair, and Xanthomonas race
specific primers were used. Our results revealed 75 presumptive strains that showed positive
results to the various phenotypic tests performed. It was observed that 13 bacterial strains were
confirmed from all four locations as X. campestries, with occurrences as follows: leaves 2 (20%),
bacterial leaf spot infected tomato seed or bulb 4 (25%), freshly harvested tomato seed 1 (25%),
root and surrounding soil 4 (13.3%), and stem 2 (13.3%). A high level of bacterial contamination
was observed on the bacterial leaf spot affected tomato samples compared to the freshly and
aseptically collected and analyzed sample. The exposure of harvested tomato bulbs to the
environment while negating appropriate interpersonal hygiene may have spawned
contamination, infection of tomato bulbs, and the distribution of the potential pathogen in the
study area. The need for appropriate implementation of inter-personal hygienic practice among
farmers while handling the tomato bulb harvest cannot be overemphasized.
KEYWORDS:Xanthomonas campestris, Xanthomonas campestris pv vesicatoria, Tomatoes, Primer fdl rp2, 16SrRNA gene sequencing
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