Long-term soil alteration in historical charcoal hearths affects Tuber melanosporum mycorrhizal development and environmental conditions for fruiting

Abstract

Abandoned charcoal hearths constitute a very particular habitat for spontaneous fruiting of Tuber melanosporum, leading some harvesters to hypothesise that the fungus could benefit from the alterations that these soils underwent. However, ecological mechanisms involved in this relation are not fully elucidated yet. As a first step to understand it, the influence of long-term soil alteration on the symbiotic stage of T. melanosporum and on selected soil properties considered key to fruiting was assessed by conducting a greenhouse bioassay and a field observational study. In the bioassay, percent root colonisation and relative abundance of T. melanosporum were significantly lower in hearth than in control soils. Hearth soils showed significantly lower resistance to penetration, larger temperature fluctuation, reduced plant cover and reduced herbaceous root abundance. The results do not support the hypothesis that soil from historical charcoal hearths currently enhances development of T. melanosporum mycorrhizas. However, whether this is due to increased infectivity of native ectomycorrhizal communities or to worse conditions for development of T. melanosporum mycorrhizas remains unresolved. Native ectomycorrhizal communities in hearths showed altered composition, although not a clear change in infectivity or richness. Direction of change in hearth soil properties is compared to alteration occurring in soils spontaneously producing T. melanosporum. The interest of these changes to improve T. melanosporum fruiting in plantations is discussed.

Chinese Black Truffle (Tuber indicum) Alters the Ectomycorrhizosphere and Endoectomycosphere Microbiome and Metabolic Profiles of the Host Tree Quercus aliena

“…This finding indicates that the ectomycorrhization has a feedback effect (modification) on soil properties, consistent with the previous studies ( Li et al, 2017 ; Yang et al, 2017 ). The soil properties, such as the soil pH, carbonate content and available calcium content, play an important role in the production of truffles ( Valverde-Asenjo et al, 2009 ; Garcia-Barreda et al, 2017 ). Therefore, the changes in soil properties may affect the growth and mycorrhizal synthesis of T. indicum .…”

Tuber melanosporum shapes nirS-type denitrifying and ammonia-oxidizing bacterial communities in Carya illinoinensis ectomycorrhizosphere soils

“…Soil microorganisms and physicochemical properties in the rhizosphere of host plant can vary with the growth of truffles, from the occurrence of ectomycorrhizae to the formation of their mature fruiting bodies ( Ponce et al, 2014 ; Barbieri et al, 2007 ; Garcia-Barreda et al, 2017 ). The microbial communities of ectomycorrhizosphere soils are verified to be different from that of rhizosphere soils in both artificial conditions and the wild ( Fu et al, 2016 ; Li et al, 2018a ; Li et al, 2018b ).…”

Edaphic and temporal patterns of Tuber melanosporum fruitbody traits and effect of localised peat-based amendment

“…There are currently over ten commercial substrates and even tractor-implements specifically designed to set up these nests. This technique is an adaptation of an old practice used by wild truffle harvesters, which consisted in the spot application of decomposed organic matter or charcoal hearth soils to amend the soil surrounding a truffière 17,18 . One of the innovative aspects of nests application in truffle orchards is the use of peat-based substrates, which clearly differ from mineral soils in many facets: low bulk density, high porosity, high aeration and good drainability, high water retention and easily available water, low thermal conductivity under equal water content and low nutrients content [19][20][21] .…”