The Science
Wildfires don’t only damage the visible parts of plants. They also affect the plant microbiome—the microorganisms living in association with plant tissues. Understanding these effects helps scientists mitigate the effects of wildfires by helping them understand how vegetation regenerates and how the plant microbiome helps the ecosystem recover. For this research, scientists examined microbial DNA samples from tissues of young quaking aspen saplings after a prescribed burn. Aspen relies largely on fire to regenerate. Before this study, scientists expected that fire would have fewer effects on the microbial communities within aspen tissues than on the microbes outside the plant. This work demonstrates that fire affects the entire plant microbiome. This means the effects of fire extend beyond the rhizosphere (the region of soil near the plant roots) and the bulk soil beyond the roots.
The Impact
Wildfires are increasing in frequency and severity. This trend can hurt forest ecosystem stability. Scientists know that the plant microbiome has a significant influence on plants’ fitness and their ability to survive stressful events such as fire. Researchers therefore need to understand the response of the plant microbiome to fire and how it helps plants recover. This study examined the leaf, stem, root, rhizome, and rhizosphere microbiomes of aspen saplings and associated bulk soil after a high-intensity prescribed fire. The results demonstrate that fire has a significant impact on the whole plant microbiome. This plant microbiome differs from the microbial habitats in the plant alone and in the soil alone. The results expand scientists’ knowledge of microbiome communities and microbiology as a whole.
Summary
This research sought to understand how fire influences the assembly and composition of the microbiome in regenerating Populus tremuloides (aspen) stands. The study found that fire severity is associated with reduced diversity of bacteria and a greatly increased dominance of fungal pathogens in the leaves of regenerating aspen. This study is the first to characterize the fire response of the whole plant microbiome, furthering knowledge of how microbial communities are assembled and are impacted by disturbance such as fire. The findings extend previous studies by revealing how the microbiomes associated with different plant tissues change in response to fire. Source tracking showed the vertical inheritance of the sapling microbiome from the parent tree. The results demonstrate the impact of fire disturbance on plant microbiome assembly and composition and suggest that additional research would facilitate enhanced plant health and ecosystem recovery after a fire.
Funding
This research was sponsored by the Genomic Science Program, United States Department of Energy Office of Science, Biological and Environmental Research program, as part of the Plant Microbe Interfaces Scientific Focus Area at Oak Ridge National Laboratory.
