Ectomycorrhizal status of a mature productive black truffle plantation

Abstract

The black truffle (Tuber melanosporum Vittad.) is an hypogeous ascomycete endemic to Mediterranean calcareous soils in southern Europe which is found in symbiotic association with roots of deciduous trees, mostly oaks (Quercus spp.) and hazelnut trees (Corylus avellana L.) (Delmas, 1978;Olivier et al., 2002).Black truffle is a first-class product, the production of which is clearly standstill after the sudden fall in the middle of 20 th century. In the f irst half of this AbstractThe truffle-plantation «Los Quejigares» was planted in 1971 by AROTZ-CATESA company. It is a 600 ha plot of Quercus ilex mycorrhizated with Tuber melanosporum at 1,250 m a.s.l. on calcareous soil. This plantation is the largest of the world and one of the eldest truffle-plantations of Spain and it is in full production. Knowledge of the mycorrhizal status of a mature black truffle plantation is significant for the improvement of truffle cultivation. Ectomycorrhizae were studied for knowing T. melanosporum persistence and diversity and abundance of other ectomycorrhizal types. Roots of 16 holmoaks were sampled, 12 trees produce truffle sporocarps and four did not. It was found a mean of about 35% of T. melanosporum ectomycorrhizae in the studied trees, being this significantly higher in the productive trees. Also, 105 more different ectomycorrhizal types were found. In spite of the high number of morphotypes found, it seems that they do not replace T. melanosporum, showing that there is a coexistence between species in the fungal community associated to the roots.Key words: AROTZ-CATESA company, characterization of ectomycorrhizae, fungal diversity, Quercus ilex, Tuber melanosporum, truffle plantations. ResumenComunidad de ectomicorrizas en una plantación adulta productora de trufa negra La plantación trufera «Los Quejigares» fue establecida en 1971 por la empresa AROTZ-CATESA. Es una parcela de 600 ha de plantas de Quercus ilex micorrizadas con Tuber melanosporum, que está situada a 1.250 m de altitud sobre suelo calizo. Esta plantación es la más grande del mundo, además de una de las más antiguas de España, y se encuentra en plena producción de trufa negra. El conocimiento del estado micorrícico de las plantaciones truferas maduras es importante para mejorar las técnicas aplicadas en la truficultura. El objetivo de este trabajo es conocer la persistencia de T. melanosporum y la diversidad y abundancia de otras ectomicorrizas que conviven con esta especie. Se muestrearon las raíces de 16 encinas, de las que 12 producían carpóforos de trufa y cuatro no. El porcentaje medio de micorrización por T. melanosporum en los árboles estudiados fue del 35%, éste porcentaje fue significativamente más alto en los árboles productores. Además, se encontraron 105 tipos de ectomicorrizas. A pesar del alto número de morfotipos encontrados, parece que éstos no producen el desplazamiento de T. melanosporum, mostrando que es posible la coexistencia entre diferentes especies pertenecientes a la comunidad de hongos asociadas a las raíces de los árboles.Palab...

Ectomycorrhizal communities above and below ground and truffle productivity in a Tuber aestivum orchard

“…Our data confirmed that the genus Tomentella is widespread and an important component in orchards with Tuber spp. (Murat et al, 2005;Pruett et al, 2008;Águeda et al, 2010;Iotti et al, 2010;Benucci et al, 2011;Belfiori et al, 2012;Leonardi et al, 2013). In agreement with Donnini et al (2008), who reported the frequent fruiting of Tricholoma species in truff ières, Tricholoma terreum was also found to be more abundant than Tuber aestivum in the present study.…”

“…Ectomycorrhizal communities on root tips in natural and cultivated truffières have been amply investigated (Donnini and Bencivenga, 1995;Donnini et al, 1999;Murat et al, 2005;Baciarelli Falini et al, 2006;Pruett et al, 2008;Águeda et al, 2010;González-Armada et al, 2010;Iotti et al, 2010;Benucci et al, 2011;Garcia-Barreda and Reyna, 2012;Leonardi et al, 2013). However, according to Tóth and Barta (2010) very few studies have simulEctomycorrhizal communities and truffle productivity 335 taneously analyzed fungal species both above and below ground in relation to varying environmental factors or with the aim of determining their suitability as indicators of environmental change.…”

Below-ground ectomycorrhizal community in natural Tuber melanosporum truffle grounds and dynamics after canopy opening

“…Since the EM fungi differ in their preference for soil depth (Courty et al 2008), the EM community is likely to differ from that in wild truffières. In addition, the abundance of T. melanosporum ectomycorrhizas in our study is lower than generally reported in truffle plantations (which are usually established with nursery-inoculated seedlings on agricultural soils), and the richness of soil-borne EM fungi is higher (Sánchez-Durán et al 2009;Águeda et al, 2010). Further study in nonproductive trees is necessary to elucidate its potential role in the renovation of truffle production.…”

Whose truffle is this? Distribution patterns of ectomycorrhizal fungal diversity inTuber melanosporumbrûlés developed in multi‐hostMediterranean plant communities

“…). Heterogeneous distributions of vegetative T. melanosporum structures were observed in previous studies comparing productive and non‐productive truffle grounds (Águeda et al ., ; Parladé et al ., ), and the biomass of mycelium in soils may vary significantly between seasons, as reported for some ECM fungal species (De la Varga et al ., ). The significant finding of our study was that some samples from immature and productive brûlés did contain high levels of truffle mycelium.…”

“…In published work dealing with the particular case of T. melanosporum truffle grounds, all vegetative parts, the ECM tips and the mycelium are generally reported to be more abundant in productive stands than non‐productive ones (Águeda et al ., ; Zampieri et al ., ; Parladé et al ., ), with few exceptions (Suz et al ., ). There is no clear threshold indicating the onset of ascocarp production (De la Varga et al ., ; Parladé et al ., ) and the presence of ECM tips can even be maintained over several decades in plantations without production (Águeda et al ., ). Similarly, the distribution of ECM tips poorly reflects the production of T. magnatum (Murat et al ., ; Leonardi et al ., ).…”