Rhizosphere solutions support stress-resistant wheat
Climate change and a growing human population present critical challenges to food production. The world needs reliable staple crops that can withstand climate-related stressors such as heat, salinity, flooding and drought. The RhizoEng project, undertaken with support from the Marie Sklodowska-Curie Actions Programme, investigated how signalling between wheat root secretions and beneficial microbes in the soil can yield hardier plants.
Building a synthetic community in the rhizosphere
The rhizosphere is the area in the soil where the metabolic functions of a plant interact with surrounding microorganisms. As plants release secretions such as amino acids, organic acids, and sugars into the soil, these root exudates act as chemical signals that attract microbes. Given this natural symbiosis, RhizoEng hypothesised that creating a synthetic community through rhizosphere engineering – manipulating the microbial consortia available to root exudates – could result in hardier, drought-resistant strains of wheat. To test this theory, RhizoEng carefully documented root exudates present in a natural soil matrix, developing a standardised and systematic pipeline for extracting these secretions. The project also conducted a pre-screening to select beneficial and responsive microbial strains. According to Marie Sklodowska-Curie Actions fellow Ajay Madhusudan Sorty: “This approach enabled us to deliver specific microbial strains alongside root exudate components as signalling molecules, ensuring the sustained presence of the inoculated strains near the root zone.”
Interdisciplinary greenhouse experiments
Chemical ecology – particularly rhizosphere engineering – is an emerging field. The project used information and approaches from several disciplines, including microbiology, plant science, molecular biology and molecular ecology to fill the knowledge gap concerning host-microbe interactions in the soil and develop a practical tool for crop cultivation. Project results were based on two meticulously run greenhouse experiments. The first identified characteristics of wheat root exudates in natural soil under drought conditions. The second trial investigated the responses of microbes beneficial to wheat. Regarding the results of the greenhouse experiments, Sorty shared: “Under stress conditions, adding synthetic root exudates as colonisation signalling mediators enhances rhizosphere chemical ecology, making this approach a robust tool to engineer wheat rhizospheres against stress-induced dysbiosis, which is an imbalance in the microbiome.”
Rhizosphere engineering in the future
RhizoEng unveiled for the first time the underground signalling behaviour of wheat root exudates under drought conditions. The innovative approach of rhizosphere engineering highlights the importance of chemical ecology to drought-resistant crop production. In the short-term, the project’s promising experimental results will be shared within academic and research communities, where the technological interventions needed to address abiotic stress management in crops can be developed. Next steps in the mid- and long-term include scaling up the strategy of rhizosphere engineering for wider application and exploring the efficacy of the approach in other crops. As Sorty points out: “We successfully identified exudates that activate beneficial counter-responses in stress-mitigating microbes, fostering overall positive interactions with host plants.” This positive outcome deserves follow up. Managing a stable food supply under adverse conditions is a looming challenge for humanity, and the results of the RhizoEng project point to a path forward.
Keywords
RhizoEng, rhizosphere, rhizosphere engineering, wheat, drought-resistant, root exudates, beneficial microbes, synthetic community, greenhouse experiments, chemical ecology
