Biological strategy applied to maize preharvest agroecosystem in Argentina to prevent fumonisin contamination

ETCHEVERRY, M.; NESCI, A.; PEREIRA, P.; SARTORI, MELINA

Bordeaux

Seminario; 12th European Fusarium Seminar; 2013

INRA

Biocontrol activity of Bacillus amyloliquefaciens and Microbacterium oleovorans, against F. verticillioides colonization of field-grown maize and fumonisin production in grains at harvest were investigated. Seed treatment during pre-sowing and spraying of maize ears during flowering were evaluated as inoculation methods of selected agents. The impact of inoculation on F. verticillioides count in maize roots and in grains at harvest level as well as on fumonisin content of the grains was evaluated in field trials  conducted under natural fungal infection and also alter inoculation with different strains of F. verticillioides. Treatments effect on maize growth and the diversity and activity of bacterial and fungal populations naturally associated with maize roots was also assessed. Additionaly, F. verticillioides count and fumonisin B1 content were significantly reduced in grains of plants grown from B. amyloliquefaciens treated  seeds. Studies on inoculums production, physiological improvement and formulation process were assessed. Cells of B. amyloliquefaciens grown in liquid media amended with glycerol showed better tolerance at low aw and high survival under heat stress. Furthermore, both biocontrol agents showed accumulation of betaine and ectoine in cells of B. amyloliquefaciens and M. oleovorans can improve the tolerance of both bacteria to water potential modifications and desiccation in the process of freeze drying and production of formulated, which could improve bacterial growth  and survival under conditions of low water availability and also increase the potential for biological control of F. verticillioides in field. MSB medium was selected for biomass production due to the high growth and survival after freeze-drying process. Formulated were development of fresh cells and freeze-dried of B. amyloliquefaciens and M. oleovorans. The efficacy of four stickers as seed coating was studied. In field trial of maize, the pre-sowing application of freeze-dried formulated B. amyloliquefaciens and M. oleovorans and paraffinic oil as sticker, caused a decrease of fumonisin B1 in grain harvest treatments including pre-sowing inoculation of F. verticillioides.