Genetic Divergence and Chemotype Diversity in the Fusarium Head Blight Pathogen Fusarium poae

Abstract

Fusarium head blight is a disease caused by a complex of Fusarium species. F. poae is omnipresent throughout Europe in spite of its low virulence. In this study, we assessed a geographically diverse collection of F. poae isolates for its genetic diversity using AFLP (Amplified Fragment Length Polymorphism). Furthermore, studying the mating type locus and chromosomal insertions, we identified hallmarks of both sexual recombination and clonal spread of successful genotypes in the population. Despite the large genetic variation found, all F. poae isolates possess the nivalenol chemotype based on Tri7 sequence analysis. Nevertheless, Tri gene clusters showed two layers of genetic variability. Firstly, the Tri1 locus was highly variable with mostly synonymous mutations and mutations in introns pointing to a strong purifying selection pressure. Secondly, in a subset of isolates, the main trichothecene gene cluster was invaded by a transposable element between Tri5 and Tri6. To investigate the impact of these variations on the phenotypic chemotype, mycotoxin production was assessed on artificial medium. Complex blends of type A and type B trichothecenes were produced but neither genetic variability in the Tri genes nor variability in the genome or geography accounted for the divergence in trichothecene production. In view of its complex chemotype, it will be of utmost interest to uncover the role of trichothecenes in virulence, spread and survival of F. poae.

At the scene of the crime: New insights into the role of weakly pathogenic members of the fusarium head blight disease complex

“…However, none of the F. poae trichothecenes could be detected during the colonization of detached leaves or wheat ears, despite the fact that in previous research we have already shown isolate 2,516 to be a DAS and NEO producer (Vanheule et al, 2017), which suggests that these toxins serve other purposes and are not involved in the competition for niche in the FHB disease complex. The situation F I G U R E 7 Principal component analysis of gene expression, fungal biomass corrected green fluorescent protein value, and normalized quantitative relative values, and the health condition of the plant (F V /F M [efficiency of photosystem II]) at 1, 2, 4, and 7 days after inoculation (dai) in ear assay.…”

“…Treating wheat fields with azole fungicides causes the Fusarium population to shift from a population dominated by F. culmorum and F. graminearum to a F. poae-dominated population (Audenaert et al, 2011). F. poae produces a complex blend of both type A (diacetoxyscirpenol [DAS] and neosolaniol [NEO]) and type B (nivalenol [NIV] and fusarenon-x [FUS-X]) trichothecenes whose function remains enigmatic (Sugiura et al, 1993;Thrane et al, 2004;Vogelgsang et al, 2008;Vanheule et al, 2017). However, no F. poae isolate has been identified that produces the virulence factor DON or its acetylated derivatives 3-acetyl DON and 15-acetyl DON, which are produced by the more aggressive pathogens in the FHB complex such as F. graminearum, F. culmorum, or F. asiaticum. In this study, we hypothesized that F. poae depends on the presence of F. graminearum to infect wheat and that the presence of F. poae influences the disease symptom development of F. graminearum in a time-dependent manner.…”

Comparative analysis of genetic structures and aggressiveness of Fusarium pseudograminearum populations from two surveys undertaken in 2008 and 2015 at two sites in the wheat belt of Western Australia

“…However, this finding is consistent with other reports of skewed mating type frequency. For example, in an analysis of geographically diverse isolates of Fusarium poae , 81% were found to be the MAT1‐1 idiomorph (Vanheule et al , ). The skewed mating type frequency found among Karlgarin isolates suggests that meiosis does not occur at high frequency within this population.…”

“…However, this finding is consistent with other reports of skewed mating type frequency. For example, in an analysis of geographically diverse isolates of Fusarium poae, 81% were found to be the MAT1-1 idiomorph ( Vanheule et al, 2017). The skewed mating type frequency Table 3 Cleaved amplified polymorphic sequence (CAPS) primers used to study the genotypic diversity of Fusarium pseudograminearum from Western Australian wheat fields.…”

Fusarium diseases: biology and management perspectives

“…Furthermore, sexual ascospores, produced in perithecia, are also able to produce infection and their role in generating genetic variation is key in the pathogenicity of Fusarium spp. (Vanheule et al 2017).…”