Vol.:(0123456789) 1 3 https://doi.org/10.1007/s00572-021-01030-9 SHORT NOTE Co‑occurrence of true truffle mycelia in Tuber magnatum fruiting sites Pamela Leonardi 1  · Riccardo Baroni 1  · Federico Puliga 1  · Mirco Iotti 2  · Elena Salerni 3  · Claudia Perini 3  · Alessandra Zambonelli 1 Received: 15 December 2020 / Accepted: 1 April 2021 © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021 Abstract Tuber magnatum (the white trufe) is the most precious species of the genus Tuber which comprises the hypogeous ecto- mycorrhizal species called “true trufe.” Despite its high economic value, the knowledge on its ecology is scant, principally due to the difculty to fnd its mycorrhizas in the soil. The possibility to detect its mycelium by DNA extracted from soil has given a new chance for studying this trufe species. In this work, the co-occurrence of other Tuber species with T. magnatum mycelium was investigated by using species-specifc primers in several productive areas located in central and northern Italy. Most (82%) of the examined soil samples showed at least one other Tuber species in addition to T. magnatum. The most common was T. maculatum (72% of soil samples) followed by T. borchii, T. rufum, T. brumale, T. dryophilum, T. macrosporum, and T. melanosporum (40%, 37%, 22%, 19%, 12%, and 1% of soil samples, respectively). Tuber aestivum was never detected in T. magnatum productive patches. Analysis of species co-occurrence showed that the pairwise associations between T. dryophilum-T. brumale, T. brumale-T. borchii, and T. borchii-T. dryophilum was signifcant. The results suggest that Tuber mycelial network in white trufe grounds is much more extensive than the distribution of their ectomycorrhizas and competitive exclusion between diferent Tuber species seems to take place only for root colonization. Keywords Tuber spp. · Italian white trufe · Soil mycelia · Soil DNA amplifcation · ITS primers Introduction The fungi of the genus Tuber (the true trufes) are hypo- geous ascomycetes which live in ectomycorrhizal associa- tion with shrubs and trees in many countries of the northern hemisphere (Tedersoo et al. 2010). Although it was esti- mated that this genus comprises 180–220 species (Bonito et al. 2010), only few of them are economically important due to the high value of their ascomata (Hall et al. 2007). Europe accounts for 85% of the world trufe export mar- ket (Gregorčič et al. 2020), where the most sought-after spe- cies are the white trufe (Tuber magnatum Picco), the black trufe (Tuber melanosporum Vittad.), the summer trufe (Tuber aestivum Vittad.), and the bianchetto trufe (Tuber borchii Vittad.). Tuber magnatum is the most valuable spe- cies, and it is considered one of the world’s great delica- cies (Mello et al. 2006). Its ascomata command retail prices varying from 1000 to 6000 €/kg in Italy but can reach higher prices outside of Italy (Zambonelli et al. 2020). Although most of the valuable Tuber species are cultivated in many parts of the world, successful T. magnatum cultivation was not achieved until recently (Hall et al. 2017; Zambonelli et al. 2020; Bach et al. 2021). This trufe species is confned to foodplains and slope feet of the Italian and Balkan penin- sula. It preferentially grows in cool and moist microhabitat of close-canopy forests with porous and soft soils (Bragato and Marjanović, 2016). Mycorrhizas of T. magnatum can be obtained in green- house but when the plants are transplanted in the feld, they seem to disappear and it is very difcult to fnd them also in correspondence of the fruiting areas (Murat et al. 2005; Bertini et al. 2006; Leonardi et al. 2013; Riccioni et al. 2016; Zambonelli et al. 2020). In contrast, mycorrhizas of other Tuber species such as Tuber dryophilum Tul. & C. Tul., * Mirco Iotti mirco.iotti@univaq.it 1 Department of Agricultural and Food Sciences, University of Bologna, viale Fanin 44, 40127 Bologna, Italy 2 Department of Life, Health and Environmental Sciences, University of L’Aquila, via Vetoio, Coppito1, 67100 L’Aquila, Italy 3 Department of Life Sciences, University of Siena, via Mattioli 4, 53100 Siena, Italy / Published online: 9 April 2021 Mycorrhiza (2021) 31:389–394