Biological control of Fusarium Head Blight

PALAZZINI J.; YERKOVICH N.; DUNLAP C.; TORRES A.; CHULZE S.

Conferencia; 13th european Fusarium Seminar; 2015

Fusarium head blight (FHB) of wheat, caused by species within the Fusarium graminearum complex, is a destructive disease that produces heavy yield losses and reduces grain quality and safety due to deoxynivalenol (DON) accumulation, a mycotoxin which can have adverse effects on animal and human health. In Argentina several epidemics with variable intensity have occurred in the last 50 years, resulting in farm income losses. Reduction of the impact of this disease can be done by chemical and/or biological control agents.The biocontrol effect of Bacillus sp. RC 218, Streptomyces sp. 87B and Brevibacillus sp. RC 263 on FHB and deoxynivalenol accumulation was evaluated in field plots in the wheat growing area of Marcos Juarez, Córdoba Province, Argentina. Spray applications of the biocontrol strains and pathogen were done at the anthesis period on the susceptible wheat cultivar BioINTA 1005. Disease incidence and severity were evaluated 16 days after treatment applications; DON accumulation on grains was determined at harvest. No statistical differences were observed in FHB incidence among the different treatments evaluated and the control treatment, averaging 19.8 % in all the plots. Bacillus sp. RC 218 showed a FHB severity reduction when applied alone, as it was demonstrated in previous studies. Streptomyces sp. 87B applied alone or in combination with the other strains, also showed disease severity reduction. The combination of the three strains showed no disease severity control. DON accumulation was reduced (68-85%) in single or dual-combined strain treatments.The genome of Bacillus sp. RC 218 that showed good biocontrol activity in reducing both FHB severity and DON accumulation was sequenced using Ion Torrent Hi-Q 400 bp sequencing technology. A draft genome of strain RC 218 was assembled at 48x coverage. The assembly yielded 67 contigs with a genome of 3.87 Mbp. The draft genome data was used for phylogenomic analysis and the strain was identified as Bacillus methylotrophicus. Data mining of the genome identified 10 gene clusters associated with potential biocontrol activity.