Mycorrhizal associations between Tuber melanosporum mycelia and transformed roots of Cistus incanus

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

“…), vary across the region (Grove & Rackham 2003; Sirami et al, 2010). 15 These vegetation types are functionally crucial because the establishment of most 16 Mediterranean tree species is often facilitated by shrubs, which buffer abiotic conditions in 17 stress-prone environments (Gomez-Aparicio et al, 2004;Holmgren et al, 2012) and play 18 roles in positive plant/plant interactions mediated by microorganisms (Selosse et al, 2006; 19 Kennedy et al, 2012). 20 Mediterranean tree species associate with particularly diversified communities of 21 ectomycorrhizal (ECM) fungi that are involved in plant nutrition (Smith & Read 2008), and 22 tolerance to water stress (Kipfer et al, 2012).…”

“…This ascomycete is an ECM fungal 9 species that non-specifically associates with various distantly related hosts in the Fagaceae 10 (Quercus), Betulaceae (Corylus), Malvaceae (Tilia) (Callot 1999) 17 period before forest canopy closure (Callot et al, 1999), within a complex mosaic of shrubs 18 and trees (Médail & Quézel 2003). In the French Mediterranean region, natural truffle 19 grounds typically consist of scattered holm oaks (Quercus ilex L.) surrounded by a few ECM 20 shrub species (Therville et al, 2013). In these dynamic plant communities, the presence of T. 21 melanosporum on roots of the different co-existing ECM hosts, its abundance and/or 22 frequency within the fungal ECM communities on the roots, and more broadly the 23 distribution of the different components of this ECM community among co-occurring ECM 24 host species have never been documented.…”

“…In these successional plant communities, we have 13 fragmentary knowledge of the distribution of T. melanosporum in space among 14 ectomycorrhizal (ECM) host species and in time. 15 Molecular identification of hosts (RFLP) and fungi (ITS sequencing) and quantification of T. 16 melanosporum mycelium (qPCR) were employed to evaluate the presence of T. 17 melanosporum on four dominant ECM host species (Quercus ilex, Q. coccifera, Arbutus 18 unedo, Cistus albidus) and the extent to which their respective ECM communities shared 19 fungal diversity, over the course of development of truffle grounds, from recent 20 unproductive brûlés to senescent ones where production has stopped. 21 We found that truffle grounds host rich communities in which multi-host fungal species 22 dominate in frequency.…”

Mycorrhized Ri-transformed roots facilitate in vitro inoculation of Cistus incanus with Tuber melanosporum

“…Transformed roots of Cistus incanus can be kept viable for several months without subculturing, much longer than the viability obtained for transformed roots of other plant species (Mills, unpublished data). Moreover, transformed roots of C. incanus are capable of entering into successful and sustainable mycorrhizal associations in vitro with T. melanosporum (Wenkart et al, 2001). These results suggest that mycorrhized transformed roots could be the key to an improved system for the production of inoculated seedlings.…”

“…After transformation with Agrobacterium rhizogenes, sterile in vitro root cultures can easily be maintained without addition of plant growth regulators (Wenkart et al, 2001). Transformed roots of Cistus incanus can be kept viable for several months without subculturing, much longer than the viability obtained for transformed roots of other plant species (Mills, unpublished data).…”