Screening Aspergillus flavus, Talaromyces purpureogenus, and Trichoderma koningiopsis for Plant-Growth-Promoting Traits: A Study on Phosphate Solubilization, IAA Production, and Siderophore Synthesis

The global rise in population has led to an increased demand for food production, necessitating the adoption of sustainable agricultural practices. Traditional methods often rely on synthetic chemicals that negatively impact both human health and the environment. This study aimed to screen soil fungal strains for plant-growth-promoting traits, specifically focusing on their ability to solubilize phosphates, produce indole-3-acetic acid (IAA), and synthesize siderophores. Fungal strains were identified using rDNA sequencing of the ITS regions, and their growth-promoting abilities were assessed in vitro. Aspergillus flavus JKJ7, Talaromyces purpureogenus JKJ12, and Trichoderma koningiopsis JKJ18 exhibited varying degrees of phosphate solubilization, with T. purpureogenus JKJ12 solubilizing the highest amount of tricalcium phosphate (TCP), while A. flavus JKJ7 was the most effective in solubilizing phytic acid calcium salt (PCS). In terms of IAA production, A. flavus JKJ7 produced the highest auxin concentration (68.51 mg/L), followed by T. koningiopsis JKJ18 and T. purpureogenus JKJ12. Additionally, A. flavus JKJ7 produced the highest amount of siderophores (83.7%), indicating its potential for improving iron uptake in plants. Principal Component Analysis (PCA) revealed distinct functional capabilities among the strains, particularly in phosphate solubilization and IAA production, suggesting their complementary use in consortium formulations. These results indicate that these fungal strains possess significant plant-growth-promoting traits and could be used as bioinoculants for sustainable agriculture, either as single strains or in combination