Use of second generation sequencing (NGS) to discover the diversity of wood-degrading fungi in Andean-Patagonian forests

Abstract

Fungi are the main degraders of wood in forest ecosystems, contributing significantly to the global carbon cycle. Metagenomic approaches based on a specific amplicon (metabarcoding) constitute a powerful tool for their prospecting and study. The main objective of this study was to characterize, through second-generation sequencing NGS, communities of degrading fungi in the sapwood of two species of Nothofagus from the forests of northern Patagonia, to evaluate diversity patterns in sites, seasons, hosts, plant compartments and health conditions, as a contribution to the autoecology of the species of this genus. Our study comprised three main methodological steps: (i) sampling of wood from healthy and diseased living trees of the forest species N. dombeyii and N. pumilio; (ii) DNA extraction, amplification and sequencing of the ITS1 region on the MiSeq Illumina platform, (iii) read processing and data extraction of the orders Polyporales and Hymenochaetales and (iv) data analysis and interpretation. A total of 35 molecular operational taxonomic units (amplicon sequence variant -ASV-) were obtained, to 23 putative fungal genera in 15 families. Postia pelliculosa was the most frequently detected species in the study. The host was the strongest factor among the variables studied in terms of its effect on the structure and composition of the fungal community analyzed. For N. dombeyi, which is distributed in a wide range of climatic conditions, the site was the strongest shaper of its communities, while for N. pumilio a greater susceptibility to changes in temperature and seasonality was discovered, which are, in fact, relevant factors for the conservation of forests in the current scenario of climate change. This is the first study to use NGS as a rapid, large-scale strategy to elucidate the diversity of wood-degrading fungi in Patagonian temperate forests.