Changes in root-associated fungal assemblages within newly established clonal biomass plantations of Salix spp.

Fungal assemblages associated with the roots of willow clones (Salix spp.) grown under short rotation intensive culture (SRIC) were isolated in order to evaluate their relationship with plant physiological (health) status, clone, geography and plant age. The assemblages were highly dominated by Fusarium (F. culmorum, F. redolens and F. equiseti), Alternaria and Phomopsis (Ascomycota); while fungi belonging to Basidiomycota and Zygomycota were only marginally present. The results suggested a shift from assemblages dominated by potentially pathogenic fungi during the first year of plant establishment to assemblages with an increased presence of potentially beneficial fungi on two-year old plants. Among the potentially pathogenic fungi, Gibberella/Fusarium and Neonectria taxa generalists appeared to be the most important threats. On the other hand, Alternaria, Penicillium and Phomopsis taxa were identified as potentially beneficial fungi given their dominance in roots of healthy plants. Differences between the assemblages of different willow clones were also evident but their implications in relation with genotype adaptability and biomass production capacity remain to be explored. Root-associated fungal assemblages appear to be useful to monitor the impacts of SRICs on the rhizosphere ecology and their study may enlighten effective ways to a proper management of these crop systems.

► A culture-based approach to study root-associated fungal assemblages of Salix clones.
► Potentially pathogenic fungi are abundant in recently planted cuttings.
► The establishment of Salix increases the abundance of potentially beneficial fungi over time.
► Differences in the composition of the fungal assemblages associated with different Salix clones.