Bacterial and fungal communities associated withTuber magnatum‐productive niches

Abstract

Truffles are hypogeous ectomycorrhizal fungi of ecological interest for forestry in soils of the northern hemisphere, and of economical relevance for food markets worldwide. The molecular mechanisms that control truffle body formation are largely unknown, as well as the environmental factors that are likely involved. Among the latter, it has been hypothesized that soil-borne communities may have an impact on truffle production. To address this question, we investigated bacterial and fungal communities resident in productive versus adjacent non-productive grounds of the white truffle Tuber magnatum by using PCR-DGGE. Although bacterial communities were generally highly similar across all samples within the grounds, profiles did cluster according to the productivity of circumscribed niches, and a Moraxella osloensis population appeared to be associated with productive sites. Fungal communities revealed several populations, yet showed no obvious patterns in relation to productivity, although Mortierella and Fusarium oxysporum appeared to be more abundant in the productive area. Our results offer a first glimpse into microbial communities thriving in truffle productive niches, and open the question as to whether microbemediated mechanisms may facilitate/inhibit truffle fruiting-body production or, vice versa, i.e. whether truffle sporocarps have an impact on the microbes living in the rhizosphere.

Growing edible mushrooms: a conversation between bacteria and fungi

“…Similarly, Tuber melanosporum ectomycorrhizae were found to harbour distinct bacterial communities from those of the bulk soil, with an enrichment in αand γ-Proteobacteria, as reflected by the amplicon pyrosequencing of PCR-barcoded libraries (Deveau et al, 2016). The investigation of communities that are resident in productive versus adjacent non-productive grounds of the white truffle, Tuber magnatum, by using PCR-denaturing gradient gel electrophoresis, found that a bacterium identified as Moraxella osloensis was associated with a productive site, and that the fungi Mortierella and Fusarium oxysporum also appeared to be more abundant in the productive area (Mello et al, 2010). Although the significance of enhanced levels of Moraxella for truffle production is unclear, Mortierella spp.…”

Truffle brûlé: an efficient fungal life strategy

“…Revolutionary insight into the truffle ecosystem dynamics based on a set of metagenomic techniques (Napoli et al, 2008Mello et al, 2010Mello et al, , 2011 suggests, but does not prove, that allelopathy may be operative in the brûlé. It should be mentioned that the allelopathic potential of truffles has already been taken into consideration by a number of researchers (Tirillini & Granetti, 1995;Tirillini & Stoppini, 1996;Chevalier, 1998;Olivier et al, 2002;Splivallo, 2007;Angelini et al, 2009).…”

Isolation of bacteria from ectomycorrhizae of Tuber aestivum Vittad

“…These approaches allowed insights into mycorrhizal community of the productive spots of T. magnatum -showing that the mycorrhizae of this fungus are generally rare and most roots of the host trees are occupied by other mycorrhizal fungi (Murat et al 2005). Molecular analysis of bacterial and fungal communitites associated with the productive spots of T. magnatum failed to identify any specific fungi associated with this truffle, whereas they suggested a bacterium Moraxella osloensis (a gamma-Proteobacterium) to be preferentially associated with the productive spots of this truffle (Mello et al 2010). Our previous study (Gryndler et al 2012) revealed a specific association of some bacteria, including four genera of actinobacterial suborder Pseudonocardineae, with ectomycorrhizae of Tuber aestivum Vittad.…”