, a new bacterial pathogen of onion causing bulb rot.

Onion bulb rot can be caused by multiple plant pathogens including bacterial pathogens. During our routine survey of commercial onion farms in 2014, 2020, and 2021, seven putative spp. strains were isolated from symptomatic onion samples in Georgia, United States. Upon fulfilling Koch's postulates on onion, a genome analysis was conducted. Whole-genome indices (ANI and dDDH) showed that the strains belonged to . Although the seven strains were not pathogenic on onion foliage, the strains were able to cause bulb rot and could also produce necrotic lesions in a red onion scale assay. populations increased significantly and to a level comparable to PNA 97-1R in a red onion scale infection assay. The core-genome analysis grouped all onion strains from Georgia together, and distinct from strains isolated from other sources and locations. Based on the genome analysis of strains (from the current study and available genomes in the repository), type I, III (Ssa-Esc and Inv-Mxi-Spa types), and V secretion systems are present in genomes, while type II, IV, and VI secretion systems are absent. However, various secondary metabolite gene clusters were identified from genomes, and a thiol/redox-associated enzyme gene cluster similar to the cluster mediating thiosulfinate tolerance was also present in onion strains of . This is the first report of as a plant pathogen.