Local population structure of Hymenoscyphus fraxineus surveyed by an enlarged set of microsatellite markers

Abstract

Summary The population structure of Hymenoscyphus fraxineus, the causal agent of ash dieback, was assessed at four closely located sites in the Czech Republic. To analyse the genetic variation, one Swiss and one Norwegian population with known population structures were selected as reference points. The analysis was performed using 16 previously published and five newly developed microsatellite markers. The quality of the new markers was assessed by sequencing the flanking region, identifying the type of the mutation and analysing the inheritance and linkage between all pairs of loci. In addition, markers were tested on 45 Japanese strains to confirm their usability on native H. fraxineus populations in Asia. One of the new markers was monomorphic in all European populations and one marker exhibited a high percentage of null alleles in the Japanese samples. Twenty markers in the four Czech populations showed lower average gene diversity than in the other two European populations. One Czech population significantly differed from all the others, with a pairwise GST of approximately 0.2, the lowest allelic richness and very low average gene diversity, likely resulting from a founder effect. The amount of genetic differentiation between the four neighbouring Czech populations exceeds the expected value from previous Europe‐wide population studies and suggests that local population dynamics can affect the population structure of H. fraxineus.

Detection of Airborne Inoculum of Hymenoscyphus fraxineus and H. albidus during Seasonal Fluctuations Associated with Absence of Apothecia

“…Since ash dieback was observed in the Czech Republic since late 1990's and detected in 2007 [22] the disease has spread over forests, plantations, urban areas, and nurseries throughout the country [23]. However, no biological studies about the causal agent of ash dieback had been carried out in our country so far.…”

“…Since then, the disease has been increasingly observed in a number of areas with different severity [23]. Therefore, the aims of this study were (i) to thoroughly describe the seasonal pattern of H. fraxineus and H. albidus ascospores dispersal in the locality where the ash dieback was firstly described in our country; (ii) to determine the influence of meteorological conditions on its biology; and (iii) to compare efficiency of rotating arm spore trap and seven-day automatic volumetric spore trap together with evaluation of the samples by qPCR.…”

Population structure of the ash dieback pathogen, Hymenoscyphus fraxineus, in relation to its mode of arrival in the UK

“…Previous studies of genetic diversity of H. fraxineus in Europe using SSR markers have indicated that European isolates come from the same source population and that differentiation between subpopulations is small, allelic variation is low and genotypic diversity is high (Gross et al ., ; Burokiene et al ., ; Haňáčková et al ., ). The only study of phenotypic variation to date reported diversity in vegetative compatibility (VC) types, a system that defines genetic individuals within a fungal population (Brasier & Webber, ).…”

Direct evidence of Hymenoscyphus fraxineus infection pathway through the petiole‐shoot junction

“…H. fraxineus was isolated from shoot segments in the proximal direction from each leaf scar and from the two-yearold shoot in cases of apparent necrosis, according to Haňáčková et al (2015). H. fraxineus was isolated from shoot segments in the proximal direction from each leaf scar and from the two-yearold shoot in cases of apparent necrosis, according to Haňáčková et al (2015).…”

“…Dead and fresh leaf petioles are colonized by multiple genotypes of the same fungal species (Gross, Zaffarano, Duo & Grünig, 2012;Hayatgheibi, 2013;Nguyen, Cleary, Enderle, Berlin, & Stenlid, 2016), and even an individual necrotic bark lesion may contain more than one genotype of H. fraxineus, as recorded by Bengtsson, Barklund, von Brömssen, and Stenlid (2014) and Haňáčková, Koukol, Havrdová, and Gross (2015). Dead and fresh leaf petioles are colonized by multiple genotypes of the same fungal species (Gross, Zaffarano, Duo & Grünig, 2012;Hayatgheibi, 2013;Nguyen, Cleary, Enderle, Berlin, & Stenlid, 2016), and even an individual necrotic bark lesion may contain more than one genotype of H. fraxineus, as recorded by Bengtsson, Barklund, von Brömssen, and Stenlid (2014) and Haňáčková, Koukol, Havrdová, and Gross (2015).…”