Isolation and Characterization of Plant Growth-Promoting Potential of Native Rhizobacteria for Biological Suppression of Fusarium Wilt in Mungbean
TL;DR
The integration of antagonistic activity with nutrient-mobilizing and phytohormone-producing capabilities highlights the potential of native rhizobacterial isolates as multifunctional bioinoculants for sustainable management of Fusarium wilt and enhancement of mungbean productivity.
Abstract
Mungbean (Vigna radiata L.) is an important grain legume crop cultivated throughout tropical and subtropical regions; however, its productivity is severely constrained by Fusarium wilt caused by Fusarium oxysporum. The present investigation aimed to isolate indigenous plant growth-promoting rhizobacteria (PGPR) from the mungbean rhizosphere and evaluate their antagonistic potential against F. oxysporum along with important plant growth-promoting attributes. Rhizospheric soil samples were collected from major mungbean-growing areas of eastern Uttar Pradesh, India. Twenty-nine bacterial isolates were initially recovered, and ten representative isolates were selected for detailed characterization. Antagonistic activity was assessed using dual culture assays, while plant growth-promoting traits including indole-3-acetic acid (IAA) production, ammonia production, phosphate solubilization, and zinc solubilization were evaluated qualitatively and quantitatively. Among the tested isolates, R-2 and R-10 exhibited the highest antifungal activity, suppressing mycelial growth of F. oxysporum by 60.0% and 57.0%, respectively. Quantitative analysis revealed that isolate R-10 produced the highest ammonia concentration (37.5 µg mL-1), phosphate solubilization index (3.30), and zinc solubilization index (3.22), whereas isolate R-2 recorded maximum IAA production (48.6 µg L-1). Molecular characterization through 16S rRNA gene sequencing identified isolate R-10 as Pseudomonas aeruginosa showing 100% sequence similarity with reference strains in the NCBI GenBank database. The integration of antagonistic activity with nutrient-mobilizing and phytohormone-producing capabilities highlights the potential of native rhizobacterial isolates as multifunctional bioinoculants for sustainable management of Fusarium wilt and enhancement of mungbean productivity. These findings support the development of eco-friendly alternatives to chemical fungicides and fertilizers in pulse-based production systems.