Population Analysis of Fusarium graminearum from Wheat Fields in Eastern China

Abstract

Wheat heads showing symptoms of Fusarium head blight were collected from four commercial fields in Zhejiang Province, China, an area where epidemics occur regularly. A total of 225 isolates were subjected to population-level analyses using restriction fragment length polymorphism (RFLP) as markers. Diagnostic RFLP markers established that all isolates belonged to Fusarium graminearum lineage 6. Nine polymorphic probes were hybridized to all isolates, resulting in 65 multilocus RFLP haplotypes (MRH). Probing with the telomeric clone pNla17, which reveals differences among isolates in the hypervariable subtelomeric region, differentiated the 65 MRH further into 144 clones. Mean gene diversity for the four field populations was similar, ranging from H = 0.306 - 0.364 over the nine RFLP loci for clone-corrected data. High levels of gene flow were inferred from a low level of population subdivision among all field populations, indicating that they were part of the same population. Pairwise linkage disequilibrium measures did not unequivocally support a random mating population, because one-third of locus pairs were significantly different from the null hypothesis of no-association between alleles. We speculate therefore that sexual recombination may not be frequent and that high levels of genotypic diversity may be maintained by relatively low selection pressure acting on a highly diverse population.

Transducin Beta-Like Gene FTL1 Is Essential for Pathogenesis in Fusarium graminearum

“…Conidia were collected from 5-day-old CMC (1.5% carboxymethylcellulose, 0.1% NH 4 NO 3 , 0.1% KH 2 PO 4 , 0.05% MgSO 4 7H 2 O, 0.1% yeast extract) cultures and resuspended in 0.01% (vol/vol) Tween 20 to a concentration of 10 6 conidia/ml. Six-week-old plants of wheat cultivar Norm were used for inoculation at flowering as described previously (15,26). The fifth, full-sized spikelet from the base of the inflorescence was injected with 10 l of the spore suspension.…”

Genetic Diversity and Fitness of Fusarium graminearum Populations from Rice in Korea

“…Studies of F. graminearum populations have been made in different geographic regions, e.g., China (12), Europe (42), the United States (48,49), and Argentina (34). Populations of F. graminearum have high levels of genotypic diversity, which suggests that recombination occurs regularly in F. graminearum populations.…”

Mycotoxin production, chemotypes and diversity of Czech Fusarium graminearum isolates on wheat

“…An especially high level of diversity was present within each location (Table 2). Other surveys of F. graminearum have similarly shown that the pathogen is genetically highly heterogeneous (Gale et al 2002;Zeller et Qu et al 2008). Based on an F ST of 0.248, the isolates originating from different locations differed significantly from one another.…”

“…Based on an F ST of 0.248, the isolates originating from different locations differed significantly from one another. The population studies of the pathogen have typically revealed a rather low F ST value, whether the host is wheat (Gale et al 2002;Zeller et al 2004) or some other crop (Naef & Defago 2006). This has been interpreted as implying that F. graminearum populations tend to display little hierarchical structure.…”

“…The genotypic survey of the present collection of F. graminearum isolates has confirmed that the pathogen population in any one location can be highly heterogeneous. This level of variability probably reflects the ability of the fungus to reproduce sexually (Bowden & Leslie 1999), the effect of which is a great enhancement of the pathogen capacity to evolve resistance to either fungicides (Gale et al 2002) or potentially to genetic resistance. r e f e r e n c e s …”