ACC-deaminase producing microbial biostimulants for agriculture and climate resilience: barriers and the way forward

abiotic stress tolerance in different crops. Besides metabolizing ACC, these biostimulants produce organic acids that help in the solubilization of phosphorous, IAA-like auxins that can enhance root growth, and siderophores that enhance iron uptake and its availability to the plants (Thakur et al., 2025).Nonetheless, several ACC-deaminase biostimulants have been identified, characterized and screened for growth promotion, but have not been commercialized on a large scale. Most of the studies on microbial biostimulants have been confined to researchers and laboratory conditions. Many factors influence the performance of these biostimulants in real-world settings. Field conditions such as soil pH, moisture, organic matter and native microbes intensely influence the effectiveness of the biostimulants by affecting microbial survival, colonization, and metabolic activity, which in turn determines their ability to promote plant growth (Azarbad & Junker, 2024). It is also important to keep in mind that biostimulants alone do not work effectively in field conditions (Shahwar et al., 2023).Long-term efficacy of biostimulants under changing climate remains uncertain. Climate change puts pressure on all sectors, particularly on those that are dependent on natural resources like agriculture. Changes in climatic conditions affect the soil's biological, chemical and physical properties, thus influencing soil health and crop productivity (Oishy et al., 2025). Climate change has worsened the catastrophic bushfire events that release carcinogenic compounds in the soil. Agricultural sector is also facing challenges to increase productivity to feed the growing global population. Unsustainable agriculture practices such as the use of chemical fertilizers put pressure on soil and lead to environmental pollution (De Corato et al., 2024).Only half of these chemical fertilizers are used by the plants, and the remaining is lost to water bodies causing eutrophication and leaching. Reflecting on the current climate change and unsustainable agriculture practice scenarios, implementation of sustainable agriculture practices is a must.A lack of farmer awareness, disbelief towards biologicals limit adoption and poor researchindustry-government linkages hinder the commercialization of the microbial biostimulants (Hasan et al., 2025). Farmers often prioritize inputs that offer short-term returns (Touch et al., 2024). Farmers training with proper demonstration trials and capacity building is a must. Also, farmers traditional knowledge should be incorporated into the field application process. Success stories must be recognised and disseminated through local languages at different farmer platforms. The dissemination of both positive and negative outcomes is equally important. Publishing negative results and conducting meta-analyses can also offer insights into context-specific relevance. Regulatory and commercial reforms with clear guidelines are also required. Governments should streamline regulations for microbial biostimulants and recognise them as distinct from chemical pesticides or fertilisers. Governments should also increase collaboration between agribusinesses startups and researchers. Regional agribusiness hubs should be established that focus on sustainable agriculture solutions and capacity building.Transparent and science-based risk assessment protocols should be developed for the application. More funding for research and development through grants should be allocated.Transdisciplinary research is also necessary to increase awareness of the role of soil health in human nutrition and health.Microbial biostimulants must be tested in diverse climatic and soil types. For instance, regions like Punjab and Haryana in India which are the hub of agriculture and currently facing issues of salinity and low level groundwater (Krishan et al., 2022;Malik et al., 2023) ; Sub-Saharan countries including Ethiopia, Kenya and Nigeria where drought and low-nutrient soils are major issues (Lombe et al., 2024); Southeast Asian countries like Philippines and Vietnam where natural disasters like typhoons affect rice production (Yuen et al., 2024) should be selected to evaluate the efficacy of native biostimulants. Countries like Australia which has seen a shift regarding extreme temperatures and lower rainfall (CSIRO, 2024) can be an important site to evaluate biostimulants efficacy. Climate-sensitive crops such as maize and rice should be prioritized for multi-locations field testing. ACCD alone may not be an effective strategy. It has been well documented that biostimulants with multiple plant growth promoting activities are more effective in enhancing plant growth, stress tolerance, and overall productivity than singular focus on one PGP traits (Gulati et al., 2024). Co-selection for other traits like biotic stress tolerance, nitrogen fixation, phosphate solubilization and siderophore production can improve efficacy and consistency (Thakur et al., 2024). Use of consortium, biochar, arbuscular mycorrhizal fungi and other organic amendments can be useful to enhance their performance under field conditions.Formatted: Font: BoldIn the future, agriculture tools such as smart sensors and AI-based decision support systems may also play a role in guiding the application of microbial biostimulants. Smart sensors provide real-time data on soil moisture, temperature, salinity and overall plant health which allow early identification of stress conditions (Pace et al., 2025). AI-based decision support systems integrate these data with weather forecasts and crop growth models to refine strain selection as well as timing and dosage of inoculation (Rezaee Danesh, 2025). This integrated approach can improve biostimulant survival, root colonization, and overall stress-alleviation performance under field conditions. Omics approaches such as transcriptomics and metabolomics can further provide insights into the biostimulants interaction with plants under field conditions.