Production and Estimation of Plant Growth Regulators in Fungi Isolated from Western Ghats

Abstract

Introduction: The Rhizosphere is the narrow region of the soil tightly adhered to the plant root system and is under the influence of metabolites released by the associated soil microorganisms. Metabolites act as chemical messengers and attract motile microorganisms, representing a nutrient source to support their growth. These microorganisms are often called plant growthpromoting microorganisms, including bacteria, fungi, actinomycetes, and cyanobacteria. Aim/Objectives: The plant growth regulators were produced from the fungi obtained from Western Ghats. The potent PGPF was selected for HPLC and pot study analysis among the isolates obtained. Also, 18s rRNA sequencing was performed to identify the genetic similarities. Methodology: Samples were collected from the rhizosphere of the Western Ghats region. They are used for isolation and partial identification of fungi. Later, organisms were subjected to IAA and GA determination up to 15 days. The estimated IAA and GA were subjected to HPLC analysis and compared with the standards. Further, the cultured filtrate of isolated organisms was tested for IAA and GA activity by performing pot analysis with Vigna radiata. The data obtained from pot studies was statistically analyzed. The potent isolated organism was further identified using molecular sequencing and bioinformatics tools. Results: The isolated organisms were partially identified as species from Aspergillus, Rhizomucor, Fusarium, Cladosporium, and Trichoderma. Among the isolated organisms, Rhizomucor had the maximum concentration of IAA (15 days incubation), and a species of Rhizomucor and Fusarium had maximum GA (15 days incubation). The presence of IAA and GA was confirmed by comparing the standard peaks obtained from HPLC analysis. Pot study analysis showed an initial increase in shoot and root length from the 5th day onwards. Based on the statistical analysis, auxin root length showed significance at 95% interval levels. Compared with databases, the sequenced data had a 99.82% identity with Mucor irregularis. Conclusion: Auxins and gibberellins produced by the isolated organisms enhanced the root and shoot length and thus can be chosen as bioinoculants.