Dhanshree M Ridhorkar¹* and Y. S. Banginwar²

¹Department of Molecular Biology and Genetic Engineering, RTMNU, Nagpur, India
²Shankarrao Bhoyar Patil Mahavidyalaya, Pulgaon, India

*Corresponding Author: Dhanshree M Ridhorkar, Department of Molecular Biology and Genetic Engineering, RTMNU, Nagpur, India.

Received: March 27, 2026; Published: April 22, 2026

Abstract

Soil microorganisms play an essential role in converting fixed or insoluble forms of phosphorus into forms that are available for plant uptake. This group includes bacteria, fungi, actinomycetes, and arbuscular mycorrhizal fungi. Among these, phosphate- solubilizing microorganisms (PSM), particularly bacteria, are highly effective in improving phosphorus availability through the mineralization of organic matter and solubilization of inorganic phosphates present in the soil. In addition to phosphorus solubilization, PSM possess several plant growth-promoting properties. They are capable of producing various bioactive compounds such as plant growth hormones (including indole-3-acetic acid (IAA), cytokinins, and gibberellins), vitamins, antibiotics, and siderophores. These substances not only stimulate plant growth but also help in suppressing soil-borne pathogens, improving soil health, and maintaining long-term soil fertility and productivity. Indole 3-acetic acid, a crucial auxin, is vital for plant growth and development as well as in plant–microbe interactions. It acts as a signaling molecule that influences root architecture, enhances cell division, and promotes elongation of plant tissues. In the rhizosphere, many beneficial bacteria synthesize IAA using root exudates as substrates. This bacterial IAA production contributes to improved root development, increased nutrient uptake and enhanced tolerance to environmental stresses such as drought, salinity, and heavy metal toxicity. The biosynthesis of IAA in bacteria is regulated by complex genetic pathways that respond to environmental conditions. These regulatory mechanisms influence plant hormonal balance and strengthen beneficial plant–microbe associations. While some pathogenic microorganisms manipulate IAA levels to favor infection, beneficial rhizobacteria utilize IAA production to promote plant growth, improve stress tolerance, and enhance nutrient use efficiency, thereby reducing the need for chemical fertilizers. In the present study, soil samples were collected from the rhizosphere of orange trees in the Kalmeshwar tehsil. The bacterial isolates obtained were evaluated for their ability to solubilize phosphate. Further investigations were carried out to assess important plant growth-promoting traits, particularly the production of indole-3-acetic acid.

Keywords: PSM; Indole-3-Acetic Acid; Chemical Fertilizers

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Citation

Citation: Dhanshree M Ridhorkar and Y. S. Banginwar. “Diversity of Indigenous Phosphate Solubilizing Microorganisms from Orange Rhizosphere in Kalmeshwar, Tahsil and Their Indole-3-Acetic Acid Production". Acta Scientific Microbiology 9.5 (2026): 20-24.

Copyright

Copyright: © 2026 Dhanshree M Ridhorkar and Y. S. Banginwar. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.