Yeasts for Sustainable Agriculture: Integrating Plant Growth Promotion and Phytopathogen Biocontrol

Abstract

Although microbial bioproducts are part of sustainable agriculture, research and commercialization have focused mainly on rhizobacteria and mycorrhizal fungi, leaving yeasts comparatively underexplored relative to other microbial groups. Where documented, several yeast species have been associated with enhanced plant performance through phytohormone synthesis, nutrient solubilization, and ACC‐deaminase activity, as well as with suppression of fungal pathogens via competition for resources, lytic enzymes, killer toxins, volatile organic compounds (VOCs), mycoparasitism, and elicitation of plant defense responses. However, the strength of evidence supporting these mechanisms varies considerably. Many reported effects have been characterized primarily in vitro or in postharvest systems; field‐level efficacy data across diverse agroecological zones remain limited, and the molecular modes of action underlying yeast–plant interactions are only partially understood. Claims of improved salinity and drought tolerance, hormone‐mediated growth promotion, and systemic resistance induction remain largely associative and require direct confirmation under field conditions. This review critically synthesizes recent advances in yeast biology relevant to sustainable agriculture, evaluates the strength of available evidence across experimental scales, and inventories commercial live‐yeast products. It identifies five priority research areas needed to bridge the gap between laboratory promise and reliable agricultural application of yeasts as dual‐purpose biostimulants and biocontrol agents.