Imma Perfetto
Cosmos science journalist
An Australian study has revealed an ingenious tactic used by wheat to withstand drought conditions – it calls in reinforcements.
The plant sends out a chemical signal to attract specialised soil bacteria which release beneficial compounds that help it resist drought and continue to grow.
The researchers behind the discovery say these bacterial species act as “probiotics for crops” and could provide a natural way to protect plants from drought.
Distinguished Professor Brajesh Singh of Western Sydney University (WSU), senior author of the study in the journal Cell Host & Microbe, says the drought-fighting bacteria and their products will help farmers to protect their crops and survive drought, while boosting yields.
“The frequency and intensity of drought stress is escalating under climate change, which poses a significant threat to global primary productivity and sustainability,” Singh says.
“The study shows that these plant-microbe partnerships can create lasting benefits for farming in dry environments, helping to tackle drought and the substantial lasting impacts on food security and environmental health.”
Singh and colleagues revealed that, under drought conditions, wheat releases the compound 4-oxoproline from its roots to recruit the bacteria Streptomyces coeruleorubidus and Leifsonia shinshuensis which produce osmolytes – which preserve osmotic balance in cells – plant hormones, and nutrient solubilisers.
When the research team reintroduced these microbes to wheat plants in dry soils, the plants grew bigger, stayed healthier, and produced more grain, even in the next generation of crops.
“S. coeruleorubidus enhances wheat drought resistance by promoting plant biomass and yield through multiple mechanisms,” the authors write, “including increased hydrogen peroxide contents in the leaves, increased leaf stomatal density, and upregulated drought-resistant genes in wheat leaves.”
“Along with other key microbes such as L. shinshuensis, [it] creates a positive legacy effect in the soil, ultimately enhancing wheat drought resilience in subsequent plant-growth cycles.”
Lead author Dr Jiayu Li, from WSU’s Hawkesbury Institute for the Environment, says that the findings of this study reveal how plants and microbes work as a team to survive stressful conditions such as drought, making sustainable and climate-smart farming a viable option.
“Our research will provide scientists and farmers a new platform to harness natural plant compounds and soil microbes as bio-based tools to protect crops from drought, mitigating the impact of drought on agricultural productivity.”
“It also provides new pathways for targeted plant breeding for climate change and extreme weather resistant crops, as these microbes even pass on ‘drought memory,’ helping the next crop cycle perform better in dry soils.”
