Fungal Diversity In Permafrost And Tallgrass Prairie Soils Under Experimental Warming
Soil fungi play a major role in terrestrial ecosystem functioning through interactions with soil structure, plants, micro- and mesofauna and nutrient cycling through predation, pathogenesis, mutualistic and saprotrophic roles. The diversity of soil fungi was assessed by sequencing their 28S rRNA gene in Alaskan permafrost and Oklahoma tallgrass prairie soils at experimental sites where the effect of climate warming is under investigation. A total of 226,695 reads were classified into 1063 genera, covering 62% of the reference dataset. Using the Bayesian Classifier offered by RDP with 50% bootstrapping classification confidence, approximately 70% of sequences remained unclassified at the genus level, although the majority (~65%) were successfully classified at the class level, which provided insight into these lesser-known fungal lineages. Compared to the more abundant sequences, a higher proportion of rare OTUs were successfully classified to genera at 50% bootstrap, indicating that the fungal rare biosphere is not composed of sequencing artifacts. There was no significant effect of warming on the fungal community structure, except perhaps for a few minor members, but there was a significant effect of sample depth in the permafrost soils. Shallow fungal communities were largely shaped by plant influences, with abundant OTUs identified as putative endophytes or pathogens. Alaskan soil alpha diversity was nearly covered by the sequencing effort. Despite overall significant community structure differences driven by variations in OTU dominance, the prairie and permafrost soils shared 90% and 63% of all fungal sequences, respectively, indicating a fungal “seed bank” common between both sites.