Fluorescent Pseudomonas species causing post-harvest decay of endives in Argentina

ABSTRACT

A post-harvest bacterial decay was observed on ready-to-use French endives in Argentina. Affected chicons showed browning and soft-rot of inner leaves and marginal necrosis. Physiological and biochemical tests allowed us to identify the isolates from endive as Pseudomonas fluorescens bv. III, Pseudomonas fluorescens bv. V, and Pseudomonas cichorii. Pathogenicity was verified on RTU healthy endives by inoculation with each bacterial species, and also with the mixture of the 3 strains. P. cichorii caused dark brown necrosis of the margins of outer leaves; both isolates of P. fluorescens caused browning and soft-rotting of inner leaves, while the mixture induced all the described symptoms, that were similar to those found in natural infection. Identity of bacterial isolates was confirmed by RFLP analysis of a PCR-DNA fragment amplified from the 16S rRNA gene. This is the first record of a post-harvest decay in endives in Argentina.