Bacterial strains isolated from diseased onion bulb rot in South Africa

Bacterial strains were isolated from onion bulbs displaying symptoms of internal rot, including light brown discolouration, maceration, and shrinkage of the fleshy scales. The affected bulbs were collected from agricultural fields in the Free State,Gauteng and Western Cape Province of South Africa. Following surface sterilisation of the entire bulb, symptomatic tissue from the internal scales was excised, macerated in sterile 1× PBS, and homogenised using a Bioreba extraction bag. The resulting suspension was serially diluted, streaked onto nutrient agar, and incubated at 28 °C for 48 hours. Distinct bacterial colonies were sub-cultured to obtain pure strains for further genomic and phenotypic characterisation. The selected isolates were analysed using housekeeping genes for their
positive or negative pathogenic response on onion bulb.