Russulaceae and Thelephoraceae form ectomycorrhizas with members of the Nyctaginaceae (Caryophyllales) in the tropical mountain rain forest of southern Ecuador

Abstract

Summary• Three members of the Nyctaginaceae, two Neea species and one Guapira species, occurred scattered within a very species-rich neotropical mountain rain forest. The three species were found to form ectomycorrhizas of very distinctive characters, while all other tree species examined formed arbuscular mycorrhizas.• The ectomycorrhizas were structurally typified according to light and transmission electron microscope investigations. The internal transcribed spacer (ITS) rDNA and part of the nuclear large subunit (LSU, 28S) rDNA of the mycorrhiza forming fungi were amplified and sequenced. Phylogenetic analyses were carried out.• Neea species 1 was found to form typical ectomycorrhizas with five different fungal species, Russula puiggarii , Lactarius sp., two Tomentella or Thelephora species, and one ascomycete. Neea species 2 and the Guapira species were associated with only one fungus each, a Tomentella/Thelephora species clustering closely together in an ITS-neighbour-joining tree. The long and fine rootlets of the Guapira species showed proximally a hyphal mantle and a Hartig net, but distally intracellular fungal colonization of the epidermis and root hair development. The ectomycorrhizal segments of the long roots of Neea species 2 displayed a hyphal mantle and a Hartig net around alive root-hair-like outgrowths of the epidermal cells.• The distribution and the evolution of ectomycorrhizas in the predominantly neotropic Nyctaginaceae are discussed.

Low diversity and high host preference of ectomycorrhizal fungi in Western Amazonia, a neotropical biodiversity hotspot

“…Thus, this study lends no support to the hypothesis of general mycobiont specificity in the plant family Nyctaginaceae (Chambers et al, 2005;Haug et al, 2005;Suvi et al, 2010). Re-analysis of the EcM fungal community of shrub 'C' of Neea sp1 (sensu Haug et al, 2005) in an Andean cloud forest revealed a species of Clavulina in addition to members of the Russulaceae and Thelephoraceae reported previously. In Yasuni, four out of six most frequent EcM fungal species displayed host preference.…”

“…In South America, this information relies on fruit-body observations (Pegler, 1983;Singer et al, 1983;Henkel et al, 2002;Laessøe and Petersen, 2008) and limited root sampling of Nyctaginaceae (Haug et al, 2005) and Dipterocarpaceae (Moyersoen, 2006). Here we tested the hypothesis that particularly Nyctaginaceae hosts associate with a few EcM fungi that belong exclusively to the Thelephoraceae and Russulaceae families (Chambers et al, 2005;Haug et al, 2005). Based on the general latitudinal biodiversity gradient (Hillebrand, 2004) and the anticipated correlation between EcM fungal and host plant diversity (Dickie, 2007), we hypothesized that EcM fungi are highly diverse in a primary neotropical forest site.…”

Genetic diversity of the endemic gourmet mushroom Thelephora ganbajun from south-western China

“…see Tometella sublilacina clustering with species in Thelephora). Similar findings have been reported in several recent studies on Tomentella/Thelephora using ITS sequences (Haug et al, 2005;Taylor & McCormick, 2008). More detailed taxonomic investigations of their microscopic and macroscopic features coupled with the analyses of multiple additional genes from more species are needed to resolve these taxonomic issues.…”

Dispersion, an Important Radiation Mechanism for Ectomycorrhizal Fungi in Neotropical Lowland Forests?

“…where patterns of host specificity were reported (Bechem & Alexander, 2011;Haug et al, 2005;Tedersoo et al, 2010a), recent tropical EcM biodiversity surveys have shown that co-occurring (sympatric) tree species including different tree families can be colonized by identical dominant EcM fungi (Diédhiou et al, 2010;Smith et al, 2011;Tedersoo et al, 2011). These sympatric tree families included the Dipterocarpaceae and Caesalpiniaceae in the Paleotropics (Tedersoo et al, 2007(Tedersoo et al, , 2011.…”

“…Recent studies indicate that trends in EcM fungal biodiversity are not simply driven by a latitudinal gradient . Biodiversity depends on the forest type under study (Brearly, 2011;Smith et al, 2011) and is also influenced by host identity (Haug et al, 2005;Tedersoo et al, 2010a). Amongst the EcM surveys in Dipterocarpaceae vegetation (see Brearly, 2011 review and references therein), comparisons could be made with a SE Asian Mixed-dipterocarp forest (Peay et al, 2010), where diversity was measured in plot size identical to this study.…”