Interannual dynamics of Tuber melanosporum and fungal communities in productive black truffle orchards amended with truffle nests

Abstract

Truffle growers devote great efforts to improve black truffle productivity, developing agronomic practices such as ‘truffle nests’ (peat amendments that are supplemented with truffle spore inoculum). It has been hypothesized that improved fruiting associated with nests is linked to stimulation of truffle mycelia previously established in soil or to changes generated in soil fungal community. To assess this, we used real-time PCR to quantify black truffle extraradical mycelium during two years after nests installation. We also characterized the fungal community via high-throughput amplicon sequencing of the ITS region of rRNA genes. We found that neither the abundance of truffle mycelium in nests nor in the soil—nest interphase was higher than in the bulk soil, which indicates that nests do not improve mycelial growth. The fungal community in nests showed lower richness and Shannon index and was compositionally different from that of soil, which suggests that nests may act as an open niche for fungal colonization that facilitates truffle fruiting. The ectomycorrhizal fungal community showed lower richness in nests. However, no negative relationships between amount of truffle mycelium and reads of other ectomycorrhizal fungi were found, thus countering the hypothesis that ectomycorrhizal competition plays a role in the nest effect.

First Report on Truffle-Inhabiting Fungi and Metagenomic Communities of Tuber Aestivum Collected in Russia

“…One of the reasons for having so many fungal symbionts is that they help truffles resist competition from other fungi and microorganisms living in the soil. The variety of fungal symbionts provides the truffle with maximum efficiency in obtaining nutrients for forming fruiting bodies (Garcia-Barreda et al 2023). Truffles are also known to grow in different ecological conditions, including various types of soils, climatic zones, and plant communities (Mrak et al 2024).…”