The potentiality of nodule-inhabiting fungi to control the growth of Fusarium oxysporum

Abstract

This study explored the isolation and characterization of non-rhizobial endophytic fungi (NREF) from plant root nodules, emphasizing their potential significance in the biological control of Fusarium oxysporum f. sp. phaseoli (Fop) and in enhancing the growth of Phaseolus vulgaris L. Seventeen fungal isolates were obtained, seven of which had substantial antagonistic activity against Fop. Morphological identification identified these isolates as Aspergillus fumigatus, Paecilomyces variotii, Talaromyces pinophilus (three isolates), Trichoderma harzianum, and Trichoderma longibrachiatum. All selected isolates were assessed for plant growth-promoting (PGP) characteristics, encompassing indole acetic acid (IAA) and gibberellic acid (GA3) production, phosphate and zinc solubilization, siderophore and ammonia (NH4) generation, and hydrolytic enzyme activities. Talaromyces pinophilus TP-BAC1 had the highest performance in most traits, with an inhibition zone of 22.5 mm. In a pot experiment, this isolate significantly (P ≤ 0.05) decreased the disease index from 81.7% in the Fusarium treatment to 15.72% in bean plants, resulting in a protection efficiency of 80.75%. Additionally, TP-BAC1 treatment increased the amount of chlorophyll, antioxidants, and membrane stability, which helped bean plants deal with stress caused by Fusarium. The results underscore the significant potential of Talaromyces pinophilus TP-BAC1 as a sustainable biocontrol agent and biofertilizer in bean cultivation, providing an ecologically friendly alternative to chemical fungicides.