Plant-Associated Yeasts: Ecology, Plant Growth Promotion, Abiotic Stress Tolerance and Biological Disease Management
A. T. Hisana Mol *
Department of Agricultural Microbiology, College of Agriculture, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala, India.
K. Surendra Gopal
Department of Agricultural Microbiology, College of Agriculture, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala, India.
*Author to whom correspondence should be addressed.
Abstract
Plant-associated yeasts are emerging as important members of plant microbial communities and show promising potential to support sustainable agricultural practices. Although yeasts have traditionally received less attention than bacteria and filamentous fungi, increasing research has highlighted their important roles in plant–microbe interactions. They can colonize different parts of plants and perform multiple functions that support plant growth, help plants cope with environmental stresses, and contribute to the suppression of plant diseases. This review explores the ecological diversity and functional roles of plant-associated yeasts, highlighting their potential applications in agriculture, with a particular focus on yeasts inhabiting the phyllosphere. Their plant growth-promoting activities, including phytohormone production, mineral nutrient solubilisation, siderophore production, ACC deaminase activity, ammonia production and polyamine synthesis, are discussed in relation to plant nutrition and development. The potential role of yeasts in mitigating abiotic stresses such as salinity, drought, temperature extremes and heavy-metal stress is also examined. In addition, this review discusses the different ways in which yeasts can suppress plant pathogens. These include competing for nutrients and space, limiting iron availability, producing antimicrobial compounds and killer toxins, releasing hydrolytic enzymes and volatile organic compounds, forming biofilms, interacting directly with pathogens, and stimulating the plant’s own defence responses. Particular attention is given to the emerging concept of multifunctional yeasts, which possess a combination of traits that promote plant growth, improve stress tolerance, and suppress plant diseases. Such yeasts may offer greater potential for agricultural applications than strains selected based on a single beneficial trait. Future studies integrating genomics, transcriptomics, metabolomics, and microbial consortia approaches may help advance the development of effective and reliable yeast-based biofertilisers, biostimulants, and biocontrol agents. Overall, plant-associated yeasts hold considerable promise as an underexplored microbial resource for supporting sustainable and environmentally friendly crop production systems.
Keywords: Plant associated yeasts, Phyllosphere, Plant growth promotion, Biocontrol, Abiotic stress, Multifunctional yeast