Clonal Expansion of the Pseudogymnoascus destructans Genotype in North America Is Accompanied by Significant Variation in Phenotypic Expression

Abstract

Pseudogymnoascus destructans is the causative agent of an emerging infectious disease that threatens populations of several North American bat species. The fungal disease was first observed in 2006 and has since caused the death of nearly six million bats. The disease, commonly known as white-nose syndrome, is characterized by a cutaneous infection with P. destructans causing erosions and ulcers in the skin of nose, ears and/or wings of bats. Previous studies based on sequences from eight loci have found that isolates of P. destructans from bats in the US all belong to one multilocus genotype. Using the same multilocus sequence typing method, we found that isolates from eastern and central Canada also had the same genotype as those from the US, consistent with the clonal expansion of P. destructans into Canada. However, our PCR fingerprinting revealed that among the 112 North American isolates we analyzed, three, all from Canada, showed minor genetic variation. Furthermore, we found significant variations among isolates in mycelial growth rate; the production of mycelial exudates; and pigment production and diffusion into agar media. These phenotypic differences were influenced by culture medium and incubation temperature, indicating significant variation in environmental condition - dependent phenotypic expression among isolates of the clonal P. destructans genotype in North America.

Detecting viable Pseudogymnoascus destructans (Ascomycota: Pseudeurotiaceae) from walls

“…Initial morphological identifications of Pd (using Gargas et al, 2009) were confirmed by sequencing as part of other studies (2012 samples: Khankhet et al, 2014;2015 samples: pers. comm. J.…”

White-Nose Syndrome fungus introduced from Europe to North America

“…Seven of the eight genes sequenced were polymorphic among the European isolates (Tables S1 and S2), sharply contrasting with the absence of variation observed across the North American isolates [4,7]. These data demonstrate the older origin of the European population of P. destructans compared with that of the North American population.…”

“…Twenty-eight P. destructans isolates, collected from Myotis bats over a five-year timeframe and covering regions in Europe with the highest number of reported cases of P. destructans infection [6] (Figure 1A), were sequenced at eight genomic loci and combined with published data from seventy-one North American isolates covering a similar range and timeframe [4,7] (see Supplemental Experimental Procedures).…”

“…Phylogenetic reconstruction identified samples from France, Germany and Belgium as the most basal ( Figure 1B). The absence of genetic variability at these eight loci in North American isolates suggested either novel appearance in the area [4,7] or recent emergence of a virulent strain of a previously benign fungus not necessarily present on bats [2]. The fact that the most common European haplotype is 100% identical at the sampled loci to the clonal haplotype from North America corroborates a recent inter-continental fungal transfer from Europe to North America [6], rather than the emergence of a virulent strain White-Nose Syndrome fungus introduced from Europe to North America Stefania Leopardi 1,2 , Damer Blake 1 , and Sébastien J. Puechmaille 3,4, *…”

Fungi on white-nose infected bats (Myotis spp.) in Eastern Canada show no decline in diversity associated with Pseudogymnoascus destructans (Ascomycota: Pseudeurotiaceae) presence

“…Some isolates were sent to taxonomic specialists for confirmation of identification, usually through a combination of morphological and molecular genetic techniques. Identifications of Pd were confirmed by sequencing as part of another study (Khankhet et al, 2014). Permanent cultures are housed in the University of Alberta Microfungus Collection and Herbarium (UAMH 11721, 11723-11725, 11732-11734, 11813, 11815-11817) and desiccant-dried samples are vouchered in the New Brunswick Museum 04840,(4942)(4943)(4944)(4945)(4946)(4947)(4948).…”