Are the rhizosphere fungal communities of Nothofagus alpina established in two different environments influenced by plant genetic diversity?

Abstract

Fungi are one of the most important soil microorganisms due to their abundance and the importance of theecosystem processes they carry out, like decomposition, nutrient cycling, and the establishment of biologicalinteractions such as mycorrhizas. Fungi can be used as bioindicators because they are highly sensitive to alterationsin their surroundings, thus being useful for monitoring ecological changes and effects of human activityon natural ecosystems. Nothofagus alpina (raulí) is an ecologically and economically important species of SouthAmerican temperate forests. It is currently included in domestication and conservation programs, and provenancetrials have been installed in different ecosystems of Patagonia. These trials are ideal for studying how treegenetics might influence the associated microbiota. Afforestation with fast-growing exotic conifers (mainly Pinusponderosa) had been promoted as an important economic activity in Patagonia, but nowadays there is an increasinginterest for the establishment of mix Pinus + Nothofagus plantations instead of monospecific Pinusstands and for using Pinus plantations as refugee for assisted Nothofagus migration. The main objective of thiswork was to explore the structure of different fungal communities in the rhizosphere of N. alpina with differentgenetic diversity (high, intermediate, and low) implanted under a native Nothofagus forest and a P. ponderosaplantation. Fingerprinting based on Temperature Gradient Gel Electrophoresis revealed differences in thestructure of the rhizosphere fungal communities. Some relationships between N. alpina genetic diversity andcomposition of rhizosphere fungal communities were observed. In the native forest, one of the provenances(intermediate genetic diversity) was associated with the highest richness of Basidiomycetes and total fungi. Inaddition, individual genetic parameters of N. alpina specimens implanted in the native forest significantly correlatedwith Ascomycetes richness. It was also found that Basidiomycetes were the dominating fungal taxa in thenative forest, and Ascomycetes in the P. ponderosa plantation. Factors as soil physicochemical characteristics andthe dominant forestry species, which provide different quantity and quality of litter inputs and are associatedwith different ectomycorrhizal fungi, seemed to be the main factors determining this significant difference betweenthe native forest and the plantation. Beyond highlighting the potential of applying soil fungi as bioindicators,our study contributes to understanding the relationship between host genetics and rhizosphere fungi.This information is relevant not only for conservation and restoration programs, but also for taking managementdecisions related with sustainable forestry and domestication of native tree species.