Truffle Microbiome Is Driven by Fruit Body Compartmentalization Rather than Soils Conditioned by Different Host Trees

Abstract

Currently. the factors that drive the microbiome associated with truffles, the most highly prized fungi in the world, are largely unknown. We demonstrate for the first time here that truffle microbiome composition is strongly driven by associated compartments rather than by symbiotic host trees.

Bacterial Communities in the Fruiting Bodies and Background Soils of the White Truffle Tuber magnatum

“…Additionally, a tissue specificity in bacterial community composition has also been evaluated, keeping separately the external region of ascomata, i.e., the peridium, and the internal one, i.e., the gleba that contains both vegetative hyphae and asci containing the spores (Balestrini et al, 2000 ). A decrease in alpha diversity between surrounding soil (productive soil) and the peridium, as previously reported for T. indicum (Liu et al, 2021 ), suggests that bacterial community selection occurs inside the ascomata. Outcomes of beta-diversity analysis suggest that the ascomata are composed of complex microniches, including bacteria associated with specific putative functions, i.e., nitrogen metabolism, and acclimation to sub-optimal temperatures, i.e., psychrophilic bacteria.…”

“…Fluorescence in situ hybridization (FISH) analysis (Antony-Babu et al, 2014 ) demonstrated that the bacterial colonization specifically occurred in the gleba hyphae but not in the asci. More recently, the assessment of microbial communities in T. indicum showed compartmentalization of bacterial and fungal communities in different ascoma tissues, as well as a correlation with soil samples surrounding fruiting bodies and bulk soils (Liu et al, 2021 ). A natural selective pressure on microbes has been proposed to explain the reduction of diversity and the presence of specific taxa inside the fruiting bodies (Liu et al, 2021 ).…”

“…More recently, the assessment of microbial communities in T. indicum showed compartmentalization of bacterial and fungal communities in different ascoma tissues, as well as a correlation with soil samples surrounding fruiting bodies and bulk soils (Liu et al, 2021 ). A natural selective pressure on microbes has been proposed to explain the reduction of diversity and the presence of specific taxa inside the fruiting bodies (Liu et al, 2021 ). T. magnatum fruiting bodies have a higher economic value than other truffle species, and the price may change in relation to fruiting body provenience, even at a local/regional scale.…”

“…Different truffle species grown in different areas were reported to be associated with different bacterial taxa (Antony-Babu et al, 2014 ; Splivallo et al, 2015 ; Niimi et al, 2021 ; Šiškovič et al, 2021 ). As for other truffle species, T. magnatum is colonized by a complex community of bacteria, and the soil of productive truffle sites appeared to harbor specific microbial consortia (Liu et al, 2021 ).…”

“…For white truffle, microbial diversity and its putative function in different compartments are less studied in comparison with other truffle species, such as T. melanosporum (Mello et al, 2013 ; Antony-Babu et al, 2014 ; Benucci and Bonito, 2016 ; Selosse et al, 2017 ). In another truffle species, T. indicum (Liu et al, 2021 ), it has been reported that microbial richness and diversity progressively decrease when assessing the surrounding unproductive soil, the soil of productive soils adhering to the truffle peridium, the peridium, and the gleba. This study aimed to test the hypothesis that the microbial community structure and its putative associated functions are different among T. magnatum -associated compartments (peridium and gleba), and among bulk soils collected in productive truffle sites and bulk soils collected outside of these sites (reported here as unproductive sites).…”