Host Phylogeny Is a Major Determinant of Fagaceae-Associated Ectomycorrhizal Fungal Community Assembly at a Regional Scale

Abstract

Environmental filtering (niche process) and dispersal limitation (neutral process) are two of the primary forces driving community assembly in ecosystems, but how these processes affect the Fagaceae-associated ectomycorrhizal (EM) fungal community at regional scales is so far poorly documented. We examined the EM fungal communities of 61 plant species in six genera belonging to the Fagaceae distributed across Chinese forest ecosystems (geographic distance up to ∼3,757 km) using Illumina Miseq sequencing of ITS2 sequences. The relative effects of environmental filtering (e.g., host plant phylogeny, soil and climate) and dispersal limitation (e.g., spatial distance) on the EM fungal community were distinguished using multiple models. In total, 2,706 operational taxonomic units (OTUs) of EM fungi, corresponding to 54 fungal lineages, were recovered at a 97% sequence similarity level. The EM fungal OTU richness was significantly affected by soil pH and nutrients and by host phylogeny. The EM fungal community composition was significantly influenced by combinations of host phylogeny, spatial distance, soil and climate. Furthermore, host phylogeny had the greatest effect on EM fungal community. The study suggests that the assembly of the EM fungal community is governed by both environmental filtering and dispersal limitation, with host effect being the most important determinant at the regional scale.

Community Assembly of Endophytic Fungi in Ectomycorrhizae of Betulaceae Plants at a Regional Scale

“…Environmental filtering (niche process) and dispersal limitation (neutral process) are two of the fundamental processes in structuring biotic community assembly (Cottenie, 2005). The effect of environmental filtering by host plants (e.g., identity and phylogeny) on root-associated fungal communities has been widely documented in previous studies (e.g., Ishida et al, 2007;Tedersoo et al, 2013;van der Linde et al, 2018;Wu et al, 2018;Schroeder et al, 2019;Sepp et al, 2019;Wang et al, 2019a,b). For example, plant identity significantly shaped rootassociated ectomycorrhizal (EM) fungal communities (Ishida et al, 2007;Tedersoo et al, 2012;van der Linde et al, 2018) and arbuscular mycorrhizal (AM) fungal communities (Martinez-Garcia et al, 2015;Ciccolini et al, 2016;Zheng et al, 2016;Sepp et al, 2019) through host specificity, generating diverse substrates and changing microhabitats (Wardle, 2006;Dickie, 2007;Aponte et al, 2010).…”

“…For example, plant identity significantly shaped rootassociated ectomycorrhizal (EM) fungal communities (Ishida et al, 2007;Tedersoo et al, 2012;van der Linde et al, 2018) and arbuscular mycorrhizal (AM) fungal communities (Martinez-Garcia et al, 2015;Ciccolini et al, 2016;Zheng et al, 2016;Sepp et al, 2019) through host specificity, generating diverse substrates and changing microhabitats (Wardle, 2006;Dickie, 2007;Aponte et al, 2010). Likewise, an increasing amount of studies have indicated that host phylogeny strongly predicts root-associated fungal communities, such as total (Wehner et al, 2014;Schroeder et al, 2019), EM (Põlme et al, 2013;Tedersoo et al, 2013;Wu et al, 2018;Wang et al, 2019a), AM (Wang et al, 2019b), pathogenic (Schroeder et al, 2019;Wang et al, 2019b), and saprotrophic (Schroeder et al, 2019) fungi. According to phylogenetic niche conservatism, closely related plants are more similar in morphological and functional traits than distantly related ones (Losos, 2008), and maybe tend to associate with more similar fungal partners.…”

“…Environmental filtering by abiotic variables (e.g., soil and climate) has also been found to impact root-associated fungal communities (e.g., Jarvis et al, 2013;Gao et al, 2015;Miyamoto et al, 2015;Mundra et al, 2016;Barnes et al, 2018;Li et al, 2018;Van Geel et al, 2018;Wu et al, 2018;Wang et al, 2019a). For instance, climate differences explained the largest variation of EM fungal community composition in two Japanese mountains (Miyamoto et al, 2015), while soil variables were the most important drivers of AM fungal community at the Europe (Van Geel et al, 2018).…”

“…Generally, geographic distance is widely hypothesized to predict biotic community distribution as the stochastic dispersal of individuals from one site to another could be hindered by the spatial distance between sites, suggesting the effect of dispersal limitation on community assembly (Hubbell, 2001). Many previous studies have demonstrated that dispersal limitation strongly determines community assembly of root-associated fungi, such as total fungi (Wehner et al, 2014;Beck et al, 2015), AM fungi (Dumbrell et al, 2010;Davison et al, 2015;Van Geel et al, 2018), and EM fungi (Tedersoo et al, 2012;Põlme et al, 2013;Matsuoka et al, 2016;van der Linde et al, 2018;Wu et al, 2018;Wang et al, 2019a) at various spatial scales and in different ecosystems. Besides the geographic distance, fungal taxa commonly show varying functional traits, such as dispersal, germination, and colonization abilities, which also contribute to dispersal limitation (Nara, 2009;Peay et al, 2012;Kivlin et al, 2014).…”

Biogeographic patterns of ectomycorrhizal fungal communities associated withCastanopsis sieboldiiacross the Japanese archipelago

“…Recently, in some pioneer studies the geographic distributions of ECM fungal communities at regional and/or continental scales were investigated (ranging from hundreds to thousands of kilometers). From these studies, it was revealed that species identity or phylogeny of host trees are one of the most important factors generating geographic structures of ECM fungal communities (Põlme et al , 2013; Roy et al 2013; van der Linde et al , 2018; Wu et al , 2018). Unlike free-living organisms, host-associated microbial communities like ECM fungi often exhibit biogeographic patterns that are related to the distribution of their hosts (Martiny et al , 2006), because of co-migration of microbes with their host species to new habitats (Kennedy et al , 2011).…”