First Report on Pseudomonas marginalis Bacterium Causing Soft Rot of Onion in Morocco

Pseudomonas marginalis is an important postharvest pathogen causing soft rot in a wide variety of harvested fruits and vegetables. Isolated strains from rotten onion bulbs based on morphological characteristics, were tested for pathogenecity on tobacco. Pathogenic strains underwent a biochemical test which detected the presence of P. marginalis. Symptoms were reproduced by inoculating this species to onion leaves and bulbs. Based on ARN16S sequencing, reported associated species (Pantoea agglomerans, Pseudomonas fluorescens, Klebsiella oxytoca) were also confirmed. This study reports for the first time the presence of P. marginalis bacterium in Morocco causing the soft rot of onion bulb, in association with Pantoea agglomerans, Pseudomonas fluorescens, and Klebsiella oxytoca.