SOME STRAINS OF BURKHOLDERIA GLADIOLI ARE POTENTIAL CANDIDATES FOR POSTHARVEST BIOCONTROL OF FUNGAL ROTS IN CITRUS AND APPLE FRUITS

Three Burkholderia gladioli strains (DISTEF), recovered from Strelitzia reginae, were biochemically and genomically characterized and evaluated as potential candidates for post harvest biocontrol of fungal rots in citrus and apple fruits. Cell and cell-free culture filtrates inhibited in vitro, to a different extent, the growth of Rhodotorula pilimanae, Penicillium digitatum, Penicillium expansum, Botrytis cinérea, Aspergillus flavus, Aspergillus ochraceus and Alternaria alternata. Conidial germination was also inhibited in liquid culture assays by bacterial cells, culture filtrates and concentrated culture filtrates. All strains completely inhibited or significantly reduced the incidence and severity of diseases caused by P. digitatum and P. expansum to orange, lemon and apple fruits after 4 days incubation at 20°C. B. gladioli strain DISTEF-G completely inhibited P. digitatum and P. expansum growth after 9 days incubation. A partial control of green and blue mould was obtained on citrus and apple wounds inoculated with culture filtrates. FAFLP analysis showed clear separation of DISTEF strains of B. gladioli from type strains of B. gladioli and B. cepacia. The results suggest that B. gladioli DISTEF-G would be an interesting microorganism for use as a biocontrol agent.