Microbial Biostimulants for Drought Resilience in Plants: Mechanisms, Plant-Microbiome Interactions, and Sustainable Agricultural Applications.

Drought stress is one of the most significant challenges for global agriculture, adversely affecting crop yields and food security. In recent years, microbial biostimulants have emerged as a promising solution to enhance plant resilience against such abiotic stresses. This review explores the mechanisms by which microbial biostimulants, including beneficial bacteria and fungi, confer drought tolerance in plants. Key interactions between plants and their associated microbiomes are highlighted, emphasizing the roles of root-associated microbes in promoting plant growth, nutrient uptake, and stress mitigation. We examine microbial-induced plant responses, including improved water relations, photosynthetic performance, and osmotic adjustment. Additionally, the review examines the sustainability of microbial biostimulant use in agricultural practices, addressing their potential to reduce reliance on chemical inputs and improve soil health. Evidence from field studies across diverse crops is also discussed, highlighting the potential of microbial biostimulants to improve plant performance and yield stability under water-limited conditions while emphasizing the context-dependent nature of their efficacy. Furthermore, we underscore the importance of microbial diversity and community composition in maximizing the benefits of biostimulants. By integrating microbial biostimulants into conventional agricultural practices, farmers can enhance drought resilience, thereby contributing to sustainable food production systems. This review aims to provide a comprehensive understanding of the interactions between microbial biostimulants and plants under drought stress, and to highlight future research directions for optimizing their use in sustainable agriculture.