First report of Geosmithia langdonii and Geosmithia spp. isolated from a decaying elm (Ulmus minor) in Geneva, Switzerland

Abstract

The mortality of a young elm Ulmus minor in 2014 in Geneva prompted a search for the microorganisms potentially involved. Symptoms included foliar chlorosis and wilting followed by defoliation of branches. Wood symptoms included a brown streaking of sap wood and brown stains in trunk and branches. The comparison of the resulting ITS rDNA sequences to the NCBI Nucleotide database allowed to identify 10 different organisms. The genus Geosmithia represented 48% of the isolates belonging to three species: Geosmithia langdonii (7 isolates) and 2 unknown morphologically and genetically different Geosmithia sp. 1 and sp. 2 (4 isolates). Geosmithia species are very little known ascomycetes, which have been recently shown to be opportunistic pathogens on broadleaved trees and conifers, living as saprobes in galleries of many bark beetle species. In the case described here, Geosmithia langdonii, and the unknown Geosmithia species were found in symptomatic wood while bark beetle galleries were found in close regions of the symptomatic wood. Geosmithia langdonii was the major fungus retrieved from the symptomatic wood and could have contributed, along with other identified fungal species, to a pathogenic complex producing symptoms similar to the ones of the Dutch Elm Disease and led to the dieback of this elm tree. Geosmithia langdonii and 2 yet unknown Geosmithia species (sp. 1 and sp. 2), different from any other reported Geosmithia species are reported from an elm tree in Switzerland for the first time.

Geosmithia-Ophiostoma: a New Fungus-Fungus Association

“…A similar effect is well known in Trichoderma fungi that not only protect plants directly by killing other fungi and nematodes but also induce resistance against plant pathogens [ 51 ]. Based on these results, Geosmithia is not a pathogen on elm, in contrast with the observation by Hänzi et al [ 60 ]. In no case, we were able to re-isolate Geosmithia from artificially infected elms, nor was it reported among the endophytic cohort of saprotrophs of elm trees [ 61 ].…”

Core endophytic mycobiome in Ulmus minor and its relation to Dutch elm disease resistance

“…Concurringly, it was identified as the dominant fungi in a U. minor tree with extensive dieback symptoms in the absence of DED pathogens (Hänzi et al, 2016). Certain Geosmithia fungi could therefore act as opportunistic or latent pathogens in elms, as previously reported by Hänzi et al (2016). The presence of this genus in the healthy tree (RIV5) suggests that it is able to live as an endophyte in latent pathogenicity.…”

“…was extremely abundant in the declining tree RIV2. Concurringly, it was identified as the dominant fungi in a U. minor tree with extensive dieback symptoms in the absence of DED pathogens (Hänzi et al, 2016). Certain Geosmithia fungi could therefore act as opportunistic or latent pathogens in elms, as previously reported by Hänzi et al (2016).…”

Symbiosis and pathogenicity of Geosmithia and Talaromyces spp. associated with the cypress bark beetles Phloeosinus spp. and their parasitoids

“…langdonii and other Geosmithia spp. from Ulmus minor afflicted with Dutch elm disease in Switzerland, although their role was not described (Hänzi et al ., 2016). Furthermore, G .…”

“…Another study reported isolation of G. langdonii and other Geosmithia spp. from Ulmus minor afflicted with Dutch elm disease in Switzerland, although their role was not described (Hänzi et al, 2016). Furthermore, G. langdonii and G. levendula produce bioactive compounds with antimicrobial and antileishmanial activities (Stodulkova et al, 2010;Malaka et al, 2013).…”