Population structure and genetic diversity of Fusarium graminearum from southwestern Russia and the Russian Far East as compared to northern Europe and North America

Authors: YLI-MATTILA, TAPANI - University Of Turku; Opoku, Joseph; Ward, Todd

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2023
Publication Date: 5/16/2023
Citation: Yli-Mattila, T., Opoku, J., Ward, T.J. 2023. Population structure and genetic diversity of Fusarium graminearum from southwestern Russia and the Russian Far East as compared to northern Europe and North America. Mycologia. 115(4):513-523. https://doi.org/10.1080/00275514.2023.2198927.
DOI: https://doi.org/10.1080/00275514.2023.2198927

Interpretive Summary: Fusarium graminearum is a fungus that causes crop diseases such as Fusarium head blight of wheat and Fusarium ear rot of corn. This fungus also contaminates grain with toxic compounds, including trichothecene mycotoxins that can be a serious threat to food safety and animal health. As part of a global effort to promote effective control of Fusarium diseases and toxins, we utilized genetic markers to identify novel populations of F. graminearum from Europe and Asia. We determined their toxin potential, diversity, geographic, and host distributions. Our results indicate that F. graminearum causing crop diseases in northern Europe (E1 population) are different from those found in southern Europe and the Asian Far East (E2 population). Our results also indicate that the E2 population in Eurasia may have recently been introduced into parts of the United States and Canada where they have rapidly increased in frequency. These results will inform disease and mycotoxin control programs critical to preventing billion-dollar annual losses to producers and processors of wheat, barley, corn, and other cereals.

Technical Abstract: Genetic variation at variable number tandem repeat (VNTR) markers was used to assess population structure and diversity among 296 Fusarium graminearum isolates from northern Europe (Finland, northwestern Russia, and Norway), southern Europe (southwestern and western Russia), and Asia (Siberia and the Russian Far East). We identified at least two highly differentiated and geographically structured genetic populations (E1 and E2) in Eurasia (FPT = 0.35). Isolates from northern Europe were almost exclusively from the E1 population (95.6%) and had the 3ADON trichothecene genotype (97.3%). In contrast, all isolates from southern Europe were from the E2 population and 94.4% had the 15ADON genotype. The E2 population also predominated in the Asian sampling locations (92.7%) where 3ADON and 15ADON genotypes occurred at nearly equal frequencies. Southern European isolates were more closely related to those from Asia (FPT = 0.06) than to geographically closer populations from northern Europe (FPT = 0.31). Northern European populations also harbored substantially less genetic diversity (Ne = 2.1) than populations in southern Europe or Asia (Ne = 3.4), indicative of a selective sweep or recent introduction and subsequent range expansion in northern Europe. Bayesian analyses incorporating previously described genetic populations from North America (NA1 and NA2) surprisingly identified NA2 and E2 as a single genetic population consistent with hypotheses of a recent Eurasian origin for NA2. Additionally, more than 10% of the isolates from Asia and southern Europe were assigned to the NA1 population, indicating recent introductions of NA1 into parts of Eurasia. Collectively, these results demonstrate there are at least three genetic populations of F. graminearum in the northern hemisphere and indicate population-level diversity in Eurasia and North America has been shaped by recent transcontinental introductions.