Researchers at the University of Kansas have uncovered how soil microbes remember drought and help plants adapt. Their study in Nature Microbiology reveals how “legacy effects” in soil influence plant growth and survival across changing climates.
Microbes shape the soil’s memory
The research team analyzed soil collected across Kansas to study how microbes adapt to local climates over time. Associate Professor Maggie Wagner, who co-authored the study, explained that bacteria, fungi and other soil organisms play key roles in carbon storage, nutrient cycling and plant health. She said her team became interested in how these microbes might retain a kind of ecological memory from their ancestors’ past experiences with drought.
According to Wagner, this microbial memory could affect how crops like corn and wheat grow under varying rainfall conditions. While precipitation clearly influences plant development, the hidden memory of the soil’s microbes may also shape plant resilience.
Understanding the science of legacy effects
Scientists have observed legacy effects before, but the genetic and biochemical details remain unclear. Wagner said her team aimed to discover which microbes and genes drive these processes. They wanted to learn how the memory of past climates transfers from soil to microbes and finally to plants.
The researchers collected soil samples from six Kansas sites, spanning the wetter east to the dry High Plains in the west. This range provided a clear gradient to test how microbial legacy effects differ by region.
Collaboration across continents
Wagner’s team partnered with scientists from the University of Nottingham in England. Although both teams shared the workload, all experiments took place at the University of Kansas using Kansas soils. The researchers wanted to see how local microbial communities influenced plant growth.
Wagner described their approach as “old-school.” They treated microbes as a black box, growing plants in soils with different drought histories. They then measured how plants performed, identifying which microbial communities proved most beneficial.
Microbial memory lasts thousands of generations
The team exposed microbial communities to either abundant water or drought for five months. Despite thousands of bacterial generations, the memory of drought remained strong. Wagner said this microbial legacy effect was particularly powerful in plants native to the same regions as the microbes, compared with introduced crops like corn.
Native plants and local microbes work together
To explore this connection, the team compared corn with a native grass called gamagrass. Early results showed that native plants aligned more closely with local microbial histories. Wagner believes this pattern reflects co-evolution. Gamagrass and its microbial partners have shared the same environment for millennia, while corn, domesticated in Central America, has only existed in Kansas for a few thousand years.
Discovering drought-related genes
The researchers also studied genetic activity in both microbes and plants. They identified one key gene, nicotianamine synthase, which helps plants absorb iron from the soil and can increase drought tolerance. The gene activated only when plants grew alongside microbes with a drought memory. Wagner said this finding revealed how microbial memory directly shapes plant responses to stress.
She added that gamagrass may hold valuable genes to improve corn’s resilience under harsh conditions. For agricultural biotechnology companies, these insights could guide the search for beneficial microbes to enhance crop performance.
A growing field with global potential
Microbial-based solutions for agriculture already form a multibillion-dollar industry, and this study adds new depth to the science behind it. Wagner’s collaborators included researchers from Kansas, California, Pennsylvania, England, Mexico and Cabo Verde.
Wagner emphasized that the project’s strength lay in its interdisciplinary nature, combining genetics, plant physiology and microbiology. The study, funded by the National Science Foundation, demonstrates how microscopic organisms preserve the memory of past droughts—and how that memory can shape the future of farming.
