Comparing genotype and chemotype of Fusarium graminearum from cereals in Ontario, Canada

Abstract

Fusarium graminearum is responsible for production of the mycotoxin deoxynivalenol (DON) on maize and wheat in Ontario, Canada. It has been understood since the early 1980s that in most parts of Canada, the predominant chemotype of F . graminearum is 15ADON, and not the 3ADON chemotype mainly found in Europe and Asia. The discovery of F . graminearum strains that did not produce DON but the structurally related 7-α hydroxy, 15-deacetylcalonectrin (3ANX) and its hydrolysis product 7-α hydroxy, 3,15-dideacetylcalonectrin to (NX) demonstrated that we still have a lot to learn about this well studied but complicated fungus. We conducted a survey of maize and wheat samples from Ontario farms. In the 2015 crop year, we isolated 86 strains and tested a representative subset of 20 using the published genetic probes for assessing genotype. We also developed a targeted LC-MS/MS method for the identification and quantitation of known toxins from this species to determine chemotype. The results showed that 80% of our strains produced some 3ANX in addition to 15ADON and one strain produced 3ANX and no 15ADON. Comparison of chemical data with genotyping revealed that in more than 50% of the cases there was no clear agreement. These data demonstrate the importance of chemical analysis for understanding the toxigenic potential of strains, especially using a LC-MS method that is capable of differentiating 3ADON and 15ADON. For this collection, genotyping of isolates did not produce reliable information on the chemotype. This is the first report of 3ANX toxin production concurrently with 15ADON and suggests that the 3ANX producers in North America likely originated from the 15ADON background.

Building on a foundation: advances in epidemiology, resistance breeding, and forecasting research for reducing the impact of fusarium head blight in wheat and barley

“…These ascocarps can act as a primary inoculum in newly established wheat fields and can result in the establishment of further 15ADON populations. When comparing the genotypes and chemotypes of F. graminearum from maize and wheat samples from farms in Ontario, Crippin et al (2019) confirmed that 15ADON is the predominant chemotype in eastern Canada and reported that 3ANX (15-deacetylcalonectrin) toxin production occurs concurrently with 15ADON. They also suggested that the 3ANX producers in North America probably originated from a 15ADON background.…”

Commercial Biocontrol Agents Reveal Contrasting Comportments Against Two Mycotoxigenic Fungi in Cereals: Fusarium Graminearum and Fusarium Verticillioides

“…Their behavior was identical in one aspect: all inhibited the peak production of 15-ADON produced by F. graminearum (see Figure A2A). 15-ADON is a precursor to the formation of DON [44]. This inhibition could therefore be a sign of an action on the biosynthesis pathway, in particular the Tri8 gene involved in the transformation of 15-ADON into DON.…”

TRI Genotyping and Chemotyping: A Balance of Power

“…For an historical account of the development of primers and PCR conditions for Fusarium genotyping see review by Pasquali and Migheli [96]. Specific TRI genes enabled differentiation between different trichothecenes: TRI3 and TRI12, for the differentiation of genotypes into 3-ADON, 15-ADON, or NIV [73,74,78,81,83,91,97] TRI7 and TRI13, for the differentiation of genotypes into DON and NIV [74,81,83,91]; and TRI1 along with its regulatory genes TRI6 and TRI10 [39] and TRI3 and TRI12 [83,98], for the differentiation of 3ANX (NX-2) and NX (NX-3) from 3-ADON, 15-ADON, and DON [82].…”

“…Some studies reported that genotyping was highly correlated to chemotyping and that trichothecene genotyping enabled rapid prediction of production of different toxins [74,83,90,95,108,134,135]. Other studies report incongruence between chemotype and genotype data and warn against using genotyping to solely identify the risk of mycotoxin production [19,37,82,87,136,137].…”