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- Cees Waalwijk (1)
Infection incidence, kernel colonisation, and mycotoxin accumulation in durum wheat inoculated with Fusarium sporotrichioides, F. langsethiae or F. poae at different growth stages
Nazari, L. ; Pattori, E. ; Somma, S. ; Manstretta, V. ; Waalwijk, C. ; Moretti, A. ; Meca, G. ; Rossi, V. - \ 2019
European Journal of Plant Pathology 153 (2019)3. - ISSN 0929-1873 - p. 715 - 729.
Fusarium head blight - HT-2 - Nivalenol - Small-grain cereals - T-2
A 2-year field experiment was conducted to determine the effects of Fusarium sporotrichioides, F. langsethiae, or F. poae on durum wheat plants artificially inoculated at different growth stages. The percentage of symptomatic kernels was similar among the three species, but incidence of infected kernels was lower for F. langsethiae. Kernel colonization was higher when plants were inoculated before and during anthesis for F. sporotrichioides and F. poae, but unaffected by timing of inoculation for F. langsethiae. Production of T-2/HT-2 toxins was higher for F. sporotrichioides than for F. langsethiae. Significant accumulations of nivalenol were detected for F. poae. Across all three species, there was a weak correlation (r = 0.16; P = 0.031) between the incidences of symptomatic and infected kernels, but a stronger correlation (r = 0.53; P < 0.001) between infection incidence and the quantity of fungal DNA (species-specific) in kernels. Mycotoxin content was correlated (r > 0.58; P < 0.007) with infection incidence or fungal DNA in kernels, but only for F. sporotrichioides and F. poae.
The geographic distribution and complex evolutionary history of the NX-2 trichothecene chemotype from Fusarium graminearum
Kelly, Amy ; Proctor, Robert H. ; Belzile, Francois ; Chulze, Sofia N. ; Clear, Randall M. ; Cowger, Christina ; Elmer, Wade ; Lee, Theresa ; Obanor, Friday ; Waalwijk, Cees ; Ward, Todd J. - \ 2016
Fungal Genetics and Biology 95 (2016). - ISSN 1087-1845 - p. 39 - 48.
Fusarium head blight - Molecular evolution - NX-2 - Phylogenetics - TRI1 - Trichothecene
Fusarium graminearum and 21 related species comprising the F. sambucinum species complex lineage 1 (FSAMSC-1) are the most important Fusarium Head Blight pathogens of cereal crops world-wide. FSAMSC-1 species typically produce type B trichothecenes. However, some F. graminearum strains were recently found to produce a novel type A trichothecene (NX-2) resulting from functional variation in the trichothecene biosynthetic enzyme Tri1. We used a PCR-RFLP assay targeting the TRI1 gene to identify the NX-2 allele among a global collection of 2515 F. graminearum. NX-2 isolates were only found in southern Canada and the northern U.S., where they were observed at low frequency (1.8%), but over a broader geographic range and set of cereal hosts than previously recognized. Phylogenetic analyses of TRI1 and adjacent genes produced gene trees that were incongruent with the history of species divergence within FSAMSC-1, indicating trans-species evolution of ancestral polymorphism. In addition, placement of NX-2 strains in the TRI1 gene tree was influenced by the accumulation of nonsynonymous substitutions associated with the evolution of the NX-2 chemotype, and a significant (P <0.001) change in selection pressure was observed along the NX-2 branch (ω = 1.16) in comparison to other branches (ω = 0.17) in the TRI1 phylogeny. Parameter estimates were consistent with positive selection for specific amino-acid changes during the evolution of NX-2, but direct tests of positive selection were not significant. Phylogenetic analyses of fourfold degenerate sites and intron sequences in TRI1 indicated the NX-2 chemotype had a single evolutionary origin and evolved recently from a type B ancestor. Our results indicate the NX-2 chemotype may be indigenous, and possibly endemic, to southern Canada and the northern U.S. In addition, we demonstrate that the evolution of TRI1 within FSAMSC-1 has been complex, with evidence of trans-species evolution and chemotype-specific shifts in selective constraint.
Biological control of Fusarium graminearum sensu stricto, causal agent of Fusarium head blight of wheat, using formulated antagonists under field conditions in Argentina
Palazzini, Juan M. ; Alberione, Enrique ; Torres, Adriana ; Donat, Christina ; Kohl, Jurgen ; Chulze, Sofia - \ 2016
Biological Control 94 (2016). - ISSN 1049-9644 - p. 56 - 61.
Bacillus subtilis RC 218 - Biological control - Brevibacillus sp. RC 263 - Fusarium graminearum - Fusarium head blight
Fusarium head blight (FHB) mainly caused by Fusarium graminearum is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. The biocontrol effect of two bacterial strains on FHB incidence, severity and deoxynivalenol (DON) accumulation in wheat was evaluated in field trials during 2010 and 2011 at Marcos Juarez, Córdoba province, Argentina. Bacillus subtilis RC 218 and Brevibacillus sp. RC 263 applied at anthesis period were evaluated through several combinations of cell type, strains, inoculum density (104 and 106cfu/ml) and physiological modification. A significant and consistent biocontrol effect on FHB severity and DON contamination was observed in all the evaluated treatments during both 2010 and 2011 field trials. Reduction in FHB severity ranged 62-76% and 42-58% for 2010 and 2011 field trials, respectively. When evaluating the effect of the combined strains (104+104 and 106+106cfu/ml), a better biocontrol effect was observed in 2010 field trial. After biocontrol treatments, no DON accumulation was observed in wheat heads; meanwhile in control plots an average of 1372μg/kg DON was detected during the two trials. FHB incidence was significantly reduced by biocontrol treatments during the 2010 field trial but not during the 2011 field trial. The results showed the effectiveness of the two formulated biological control agents in reducing both FHB severity and DON accumulation by F. graminearum under semi controlled field conditions.