Effect of wheat infection timing on fusarium head blight causal agents and secondary metabolites in grain

Authors: BECCARI, GIOVANNI - University Of Perugia; ARELLANO, CONSUELO - North Carolina State University; COVARELLI, LORENZO - University Of Perugia; TINI, FRANCESCO - University Of Perugia; SULYOK, MICHAEL - University Of Natural Resources & Applied Life Sciences - Austria; Cowger, Christina

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2018
Publication Date: 2/2/2019
Citation: Beccari, G., Arellano, C., Covarelli, L., Tini, F., Sulyok, M., Cowger, C. 2019. Effect of wheat infection timing on fusarium head blight causal agents and secondary metabolites in grain. International Journal of Food Microbiology. 290:214-225.

Interpretive Summary: Fusarium head blight (FHB) results in yield loss and damaging contamination of cereal grains and can be caused by several Fusarium species. Our goal was to determine, in a greenhouse experiment on soft wheat, how FHB was affected by timing of infection (0, 3, 6 or 9 days after flowering) by the aggressive species F. graminearum compared to the relatively weak species F. avenaceum, F. poae and F. acuminatum. We measured FHB development as symptoms in heads, the biomass (fungal colonization) in the heads, and the amount of fungal products called secondary metabolites in kernels. These products can include mycotoxins, like deoxynivalenol (DON). With regard to symptoms, F. graminearum was unaffected by inoculation timing, while the weaker pathogens caused greater disease severity at later timings. In contrast, F. graminearum biomass was strongly affected by inoculation timing -- there was more at the middle two timings than at the earliest and latest -- while biomass of the weaker pathogens was less influenced. Similarly, F. graminearum secondary metabolite accumulation was affected by inoculation timing (more at the middle two timings than at the earliest and latest), while that of the weaker species was less affected. However, secondary metabolites produced by these weaker species tended to be higher from intermediate-late inoculations (6 daa). Overall, infection timing appeared to play a role particularly in F. graminearum colonization and secondary metabolite accumulation. It appears that secondary metabolites of weaker Fusarium species may be relatively more abundant when environmental conditions promote spore liberation later in the flowering process, while metabolites produced by F. graminearum are relatively favored by earlier conducive conditions.

Technical Abstract: Fusarium head blight (FHB) results in yield loss and damaging contamination of cereal grains and can be caused by several Fusarium species. The objective of the present study was to determine, in a greenhouse experiment on soft wheat, how FHB was affected by timing of infection (0, 3, 6 or 9 days after anthesis, daa) by the aggressive species F. graminearum compared to the relatively weak species F. avenaceum, F. poae and F. acuminatum. Measures of FHB development were: symptoms in heads (visually assessed), fungal biomass (quantified by q-PCR) and accumulation of fungal secondary metabolites (quantified by LC-MS/MS) in kernels. With regard to symptoms, F. graminearum was unaffected by inoculation timing, while the weaker pathogens caused greater disease severity at later timings. In contrast, the accumulation of F. graminearum biomass was strongly affected by inoculation timing (3 daa = 6 daa = 0 daa = 9 daa), while colonization by the weaker pathogens was less influenced. Similarly, F. graminearum secondary metabolite accumulation was affected by inoculation timing (3 daa = 6 daa = 0 daa = 9 daa), while that of the weaker species was less affected. However, secondary metabolites produced by these weaker species tended to be higher from intermediate-late inoculations (6 daa). Overall, infection timing appeared to play a role particularly in F. graminearum colonization and secondary metabolite accumulation. However, secondary metabolites of weaker Fusarium species may be relatively more abundant when environmental conditions promote spore liberation later in anthesis, while metabolites produced by F. graminearum are relatively favored by earlier conducive conditions.