Burkholderia Tropicalis, a Potential Bacterial Inoculant to Control Nematodes and Improve Sugarcane Growth

The bacterial genus Burkholderia is abundant in the sugarcane rhizosphere. Literature states that some Burkholderia strains are nematode and fungal antagonists and/or plant growth promoters. Research was undertaken to obtain indigenous sugarcane-associated Burkholderia strains that possess these properties. Preliminary screening produced 13 isolates that are able to paralyse juveniles of Meloidogyne spp. This collection of isolates comprised Burkholderia cepacia complex, B. gladioli, B. caribensis, B. fungorum and a new species, B. tropicalis. Since B. cepacia complex and B. fungorum are associated with hospital infections, these species were omitted from further study. B. gladioli is often a mild plant pathogen, and was thus also eliminated. B. tropicalis, which has never been associated with clinical cases, was found to be an endophyte that enhances maize growth and fixes nitrogen. Consequently, search was made in sugarcane for N-fixing strains of B. tropicalis that are antagonistic to plant parasitic nematodes and various plant pathogens such as the smut fungus, Ustilago scitaminea, and Fusarium spp. Strain LM1-376.8 belongs to B. tropicalis and has been isolated from the rhizosphere of sugarcane. It fixes nitrogen and is antagonistic to nematodes, but not to certain pathogenic fungi. A culture medium has been designed for the isolation of more N-fixing B. tropicalis. To confirm the identification of B. tropicalis, a speciesspecific PCR was designed. The expected outcome of this research is the selection of strains whose inoculation would benefit sugarcane yield through a combination of anti-nematode, anti-fungal and growth promotion properties.