Soil Metatranscriptomes Under Long-Term Experimental Warming and Drying: Fungi Allocate Resources to Cell Metabolic Maintenance Rather Than Decay

Abstract

Earth’s temperature is rising, and with this increase, fungal communities are responding and affecting soil carbon processes. At a long-term soil-warming experiment in a boreal forest in interior Alaska, warming and warming-associated drying alters the function of microbes, and thus, decomposition of carbon. But what genetic mechanisms and resource allocation strategies are behind these community shifts and soil carbon changes? Here, we evaluate fungal resource allocation efforts under long-term experimental warming (including associated drying) using soil metatranscriptomics. We profiled resource allocation efforts toward decomposition and cell metabolic maintenance, and we characterized community composition. We found that under the warming treatment, fungi allocate resources to cell metabolic maintenance at the expense of allocating resources to decomposition. In addition, we found that fungal orders that house taxa with stress-tolerant traits were more abundant under the warmed treatment compared to control conditions. Our results suggest that the warming treatment elicits an ecological tradeoff in resource allocation in the fungal communities, with potential to change ecosystem-scale carbon dynamics. Fungi preferentially invest in mechanisms that will ensure survival under warming and drying, such as cell metabolic maintenance, rather than in decomposition. Through metatranscriptomes, we provide mechanistic insight behind the response of fungi to climate change and consequences to soil carbon processes.

Climate change effects on plant-soil feedbacks and consequences for biodiversity and functioning of terrestrial ecosystems

“…Recalcitrant litter would, however, promote microbial communities specialized in degrading complex plant polymers ( 70 ), so slow microbial metabolism and nutrient release will favor slow-growing plant species. Furthermore, under warmer and drier conditions, fungal metabolism can shift toward maintenance at the expense of the production of enzymes that break down plant-carbon compounds, with concomitant effects on plant communities and ecosystem carbon dynamics ( 71 ). Under different scenarios, it is likely that communities dominated by fast-growing species will continue to produce high-quality litter, which may promote soil microbial communities that will decompose litter at faster rates ( 72 ), maintaining high soil nutrient availability where fast-growing species thrive (Fig.…”

Exploring Trait Trade-Offs for Fungal Decomposers in a Southern California Grassland

“…In contrast, trade-offs between resource acquisition and the other traits are less commonly studied. However, there is some support for trade-offs between stress tolerance and extracellular enzyme production, particularly for yeast ( Treseder and Lennon, 2015 ; Morrison et al, 2018 ; Romero-Olivares et al, 2019 ). Soil microbial communities also exhibit trade-offs between C use efficiency, which could be a proxy for growth yield, and extracellular enzyme activity, especially for C-associated enzyme activity ( Malik et al, 2019 ).…”

Identifying Functional Impacts of Heat-Resistant Fungi on Boreal Forest Recovery After Wildfire

“…During decomposition, C can be retained in mineral soil (Prescott, 2010), in undecomposed mycelial networks (Clemmensen et al, 2013), or in soil fauna. Soil warming, which may be enhanced postfire, can alter fungal communities and reduce resource allocation to decomposition activities (Asemaninejad et al, 2017;Romero-Olivares et al, 2019). Thus, the association between decomposers, CO 2 or CH 4 fluxes, and accumulation of soil organic matter is not always clear (Allison et al, 2010;Kyaschenko et al, 2017).…”