“That’s kind of the missing link.” Maggie Wagner, an associate professor of ecology and evolutionary biology at the University of Kansas, recently led a study investigating that link. This work underlines the role of microbial “legacy effects” in soils across the state. The recent research appearing in Nature Microbiology underscores the incredible capacity of microbial communities to recall bygone environmental states, such as drought. This memory is incredibly powerful with regards to plant performance.
In 2020, researchers gathered soil samples from six varied sites throughout Kansas. They traveled through the historically more humid eastern part of the state as well as the drier western High Plains. Wagner and her colleagues performed genetic and genomic analyses of microbes and plants. Their goal was to better understand how these legacy effects, compounded by the realities of climate change, are affecting agriculture. Those discoveries might turn out to be critical for farmers hoping to use those beneficial microbes to improve crop yields.
Exploring Soil Samples Across Kansas
Wagner’s team collected soil samples from six different Kansas sites. They’re assessing how different moisture contents impact the microbial communities. The researchers wanted to get to the bottom of how important legacy effects are in soils. They were particularly interested in how historical conditions shape present-day interactions between microbes and plants.
The experimental design stressed microbial communities by subjecting them to either excess water or drought conditions over a 5-month period. In Wagner’s view, this methodology was essential for making sense of the long-term ramifications of these legacy effects.
“We divided up the work, but the bulk of the experiment—actually, the entire experiment—was conducted here at KU, and we also focused on soils from Kansas for this work.” – Maggie Wagner
By using a controlled and rigorous experimental approach, the researchers were able to see how different microbial communities responded to historic drought scenarios. This exploration surfaced important ecological relationships that can beautify agricultural practices sustainably.
The Significance of Microbial Legacy Effects
Wagner further observed that although legacy effects are known from past studies, they are still not well characterized. Curious about this knowledge gap, her team set out to better understand how the genetic mechanisms behind microbial memory worked. In their experiments, drought conditions were still able to impact soil microbial communities, even after thousands bacterial generations. The effects on the communities were still very much apparent.
“Even after many thousands of bacterial generations, the memory of drought was still detectable,” – Maggie Wagner
One outcome of the study was identifying the gene “nicotianamine synthase” as of high significance. This implies this gene may be an important driver of the legacy effects we observed. This important discovery now lays the foundation for research to explore how particular genes are responsible for shaping plant growth inherited from ancient soil environments.
Wagner described the larger implications of their study, telling us that an interest in bioengineering agriculture starts with knowing the world of microbial memory.
“We thought this was really fascinating. It has a lot of important implications for how we can grow plants, including things like corn and wheat,” – Maggie Wagner
Implications for Agriculture and Microbial Commercialization
The commercial potential for realizing the microbial legacy effects is huge. The microbial commercialization sector in agriculture is a multibillion-dollar industry, and it’s growing. Wagner added that findings from this work will help inform biotech companies looking to develop advantageous microbes for agriculture.
“For biotech firms focused on microbial additions to crops, this gives hints about where to look for [microbes] with beneficial properties. Microbial commercialization in agriculture is a multibillion dollar industry and still growing,” – Maggie Wagner
Soil health matters Current soil conditions are an immediate concern for plant health. Moreover, the past trajectories of microbial communities’ history is key to this compatibility. Knowing exactly which microbes are doing what at a genetic level will be key to unlocking a more sustainable agricultural future.
As Wagner concluded, we need to do much more research about how these legacy effects work. She stated,
“We don’t really understand how legacy effects work,” – Maggie Wagner
The complex relationships between soil microbes and plant growth present numerous questions for future studies, particularly regarding nutrient movement and carbon sequestration.