Boosting Plant Growth with Helpful Bacteria from Rosemary

Jenn Hoskins
4th June, 2024

Boosting Plant Growth with Helpful Bacteria from Rosemary

Image Source: Natural Science News, 2024

Key Findings

  • The Indian Agricultural Research Institute studied Bacillus subtilis KU21 from rosemary roots for its plant growth-promoting abilities
  • B. subtilis KU21 can solubilize phosphate, making it more accessible to plants, which is crucial for their growth
  • In tests on tomato plants, B. subtilis KU21 significantly improved seed germination, plant growth, nutrient uptake, and soil quality
The Indian Agricultural Research Institute recently conducted a study to evaluate the plant growth-promoting (PGP) potential of the endophytic strain Bacillus subtilis KU21 isolated from the roots of Rosmarinus officinalis[1]. This strain exhibited multiple PGP traits, including phosphate solubilization, nitrogen fixation, indole-3-acetic acid (IAA) production, siderophore production, hydrogen cyanide (HCN) production, lytic enzyme production, and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Additionally, B. subtilis KU21 showed antagonistic activity against phytopathogenic fungi such as Fusarium oxysporum, Fusarium graminearum, and Rhizoctonia solani. The study highlighted the ability of B. subtilis KU21 to solubilize phosphate, a crucial nutrient for plant growth, through the production of gluconic acid, facilitated by the glucose dehydrogenase (gdh) gene. This finding is significant because phosphate is often present in insoluble forms in the soil, making it inaccessible to plants. By solubilizing phosphate, B. subtilis KU21 can enhance nutrient availability and uptake by plants. To assess the practical applications of this strain, the researchers conducted in vivo growth promotion studies on tomato plants under net house conditions. The results were promising, showing a remarkable increase in seed germination, plant growth parameters, nutrient acquisition, and soil quality parameters (NPK) in B. subtilis KU21-treated plants compared to untreated controls. These findings suggest that the use of this strain could support sustainable tomato production in the Northwest Himalayan region without compromising soil health and fertility. This study builds on previous research that has explored the potential of plant growth-promoting rhizobacteria (PGPR) and endophytic bacteria to enhance crop growth and reduce reliance on chemical fertilizers. For instance, a study on banana plants demonstrated that inoculation with Bacillus amyloliquefaciens Bs006 and Pseudomonas fluorescens Ps006 could partially replace chemical fertilization, promoting plant growth similarly or even slightly superior to 100% chemical fertilization[2]. Similarly, another study isolated and identified root endophytic bacteria from Rosmarinus officinalis that exhibited various PGP traits and significantly increased the growth parameters of the plant[3]. The current study aligns with these findings, further validating the potential of specific bacterial strains to enhance plant growth and soil health. The mechanisms by which these bacterial strains promote plant growth are multifaceted. For example, the production of IAA, a plant hormone, can stimulate root elongation and branching, leading to better nutrient and water uptake. Siderophore production helps in sequestering iron from the soil, making it more available to plants, which is crucial for various metabolic processes. The production of lytic enzymes and HCN can suppress soil-borne pathogens, thereby reducing disease incidence and promoting healthier plant growth. Moreover, the ability of B. subtilis KU21 to fix nitrogen is particularly beneficial in agricultural systems where nitrogen is a limiting factor. Nitrogen fixation refers to the conversion of atmospheric nitrogen into a form that plants can use, thereby reducing the need for synthetic nitrogen fertilizers, which can be costly and environmentally harmful. In summary, the study conducted by the Indian Agricultural Research Institute provides compelling evidence for the use of Bacillus subtilis KU21 as a biofertilizer to promote sustainable tomato production. By enhancing nutrient availability, suppressing pathogens, and improving soil health, this strain offers a viable alternative to chemical fertilizers, aligning with broader efforts to develop sustainable agricultural practices. The findings also underscore the importance of exploring and harnessing the potential of plant-associated bacteria to address agricultural challenges and improve crop productivity.

AgricultureBiochemPlant Science


Main Study

1) Assessment of Plant Growth Promotion Potential of Endophytic Bacterium B. subtilis KU21 Isolated from Rosmarinus officinalis.

Published 4th June, 2024

Journal: Current microbiology

Issue: Vol 81, Issue 7, Jun 2024

Related Studies

2) Screening, plant growth promotion and root colonization pattern of two rhizobacteria (Pseudomonas fluorescens Ps006 and Bacillus amyloliquefaciens Bs006) on banana cv. Williams (Musa acuminata Colla).

3) Bioprospecting beneficial endophytic bacterial communities associated with Rosmarinus officinalis for sustaining plant health and productivity.

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