Ecological and molecular studies of fungal communities associated with roots of Salix spp. grown under high density, short rotation intensive culture

Abstract

In Canada, willow (Salix spp.) short rotation intensive cultures (SRIC) have been established to investigate their potential to produce biomass for bioenergy. Since root-associated fungal communities are involved in plant nutrition and disease susceptibility, it is relevant to understand their interactions with willows and their role on the sustainability of SRIC. In this project traditional methods together with molecular techniques were used to: i) assess the diversity of fungal communities in roots of willows and their relationship with major characteristics of SRIC ii) evaluate the effects on plant development of potentially beneficial and pathogenic fungi, and iii) identify arbuscular mycorrhizal fungal (AMF) species and their interaction with promising Salix clones.

Potentially pathogenic fungi were more dominant in diseased and recently planted cuttings than in healthy older ones. This suggested the occurrence of a positive shift prompted by the establishment of the cuttings on the site. Gibberella/Fusarium sp. and Neonectria sp. were the most dominant taxa particularly in diseased plants. Under greenhouse conditions the inoculation with potentially beneficial and potentially pathogenic fungi induced significant differences in root biomass but not in overall aerial biomass production. PCR-denaturing gradient gel electrophoresis was successfully standardized and used to identify arbuscular mycorrhizal fungal species associated with different clones. The results indicated a degree of specificity between AMF species and plant genotype.

Root-associated fungal communities appear to be useful to monitor the impacts of SRIC on soil ecology and their study may enlighten effective ways to increase the productivity of these biomass systems.