Latitudinal variation in mycorrhizal diversity associated with a European orchid

Abstract

Aim Biodiversity is known to be unevenly distributed along latitudinal gradients. While this pattern has been observed for many different organisms, it is unclear whether the distributions of ecologically important belowground mutualists, such as orchid mycorrhizal fungi (OMF), also vary according to latitude. Location Europe. Taxon Spiranthes spiralis (L. Chevall) Orchidaceae. Methods We sampled 37 populations over a >3,000 km latitudinal gradient of the European orchid Spiranthes spiralis to test whether the diversity and community composition of OMF are influenced by latitude. For this, we sequenced the broad spectrum ITS3/4OF region to identify OMF and quantified environmental variables that may influence their occurrence. To assess whether seed germination was affected by suitable OMF in different regions, we performed a reciprocal translocation germination experiment at the northern, central and southern part of its range. Results In total, 75 OMF taxa were associated with S. spiralis, the majority belonging to the Ceratobasidiaceae and Thelephoraceae. Both taxonomic and phylogenetic OMF diversity decreased with increasing latitude. Three Ceratobasidiaceae taxa were widespread, but the number of sequences of two of these taxa decreased with increasing latitude. Reciprocal translocation germination experiments revealed that S. spiralis seeds germinated in each region regardless of seed provenance, but germination rates were highest in the southern part of its range where mycorrhizal diversity was highest. Main conclusions OMF diversity decreased with increasing latitude, indicating that communities of OMF may be shaped by latitudinal gradients. These results highlight the need to understand the factors that determine the distribution of belowground mutualists, which are essential to predict how plant distributions will shift under future environmental change.

Similarity in mycorrhizal communities associating with two widespread terrestrial orchids decays with distance

“…Epipactis, fungal community, Gymnadenia, mycorrhizal specificity, orchid mycorrhiza, spatial turnover decreases with increasing latitude (Duffy et al, 2019), and that the community composition of OMF varies according to habitat (Jacquemyn, Waud, Merckx, et al, 2016).…”

“…The few available studies (Davis, Phillips, Wright, Linde, & Dixon, 2015;Duffy, Waud, Schatz, Petanidou, & Jacquemyn, 2019;Girlanda et al, 2006;Irwin, Bougoure, & Dearnaley, 2007;Otero, Flanagan, Herre, Ackerman, & Bayman, 2007;Roy et al, 2009;Selosse, Weiß, Jany, & Tillier, 2002;Taylor, Bruns, & Hodges, 2004;Těšitelová et al, 2015) that have attempted to sample the large-scale distribution of mycorrhizal fungi associating with a particular orchid species have shown that the wide distribution of some orchid species may to some extent be explained by the widespread occurrence of its mycorrhizae. For example, Davis et al (2015) showed that the Australian orchid Pheladenia deformis associates with one or two Sebacina sp., but that these fungi have a widespread distribution across the Australian continent.…”

“…Because many orchid species show more generalist interactions and associate with several different fungi (Girlanda et al, ; Jacquemyn, Brys, Lievens, & Wiegand, ; Roy et al, ; Selosse et al, ) and because soil fungal communities can vary strongly in space (Talbot et al, ), this possibly leads to turnover in mycorrhizal partners across large geographical areas and a significant decrease in similarity in mycorrhizal communities with increasing distance, that is, distance decay of similarity (Nekola & White, ; Soininen, Mcdonald, & Hillebrand, ; Talbot et al, ). Indeed, recent research has already indicated that OMF diversity decreases with increasing latitude (Duffy et al, ), and that the community composition of OMF varies according to habitat (Jacquemyn, Waud, Merckx, et al, ).…”

Similar mycorrhizal fungal communities associated with epiphytic and lithophytic orchids of Coelogyne corymbosa

“…In previous studies, arbuscular mycorrhizal, ectomycorrhizal, and ericoid mycorrhizal fungal communities have been found to be shaped by elevational gradients ( Gai et al., 2012 ; Gorzelak et al., 2012 ; Looney et al., 2016 ) . Mycorrhizal fungi of one terrestrial orchid species also change with latitudinal variation ( Duffy et al., 2019 ), and further comparisons of the mycobionts of epiphytic orchids along elevational and latitudinal gradients will be meaningful.…”

“…C. corymbosa is also the species with the northern-most distribution within the genus. Given that mycorrhizal fungal species compositions can be affected by the geographic distribution of plant hosts ( Gai et al., 2012 ; Gorzelak et al., 2012 ; Looney et al., 2016 ; Duffy et al., 2019 ), we speculated that there are differences in the OMF composition between C. corymbosa and its tropical relatives, and between epiphytic and lithophytic individuals of the species.…”