Rice seedlings enhanced by bacteria in a salt-affected field

Can Tiny Bacteria Save Our Rice? The Promising Power of Plant Growth-Promoting Rhizobacteria

Kai Mendoza in Climate & Environment August 2025 • 4 min read.

"Discover how ACC deaminase-producing bacteria can enhance rice growth and salt tolerance, offering a sustainable solution for agriculture."

In an era defined by increasing environmental challenges, ensuring food security is more critical than ever. Among these challenges, soil salinity stands out as a major threat to agricultural productivity worldwide. Saline soils, characterized by high salt concentrations, inhibit plant growth, reduce crop yields, and endanger the livelihoods of farmers. According to the Food and Agricultural Organization (FAO), soil salinity is projected to devastate 50% of arable lands by 2050. Rice, a staple food for billions, faces significant threats from this growing problem.

Traditional methods of combating soil salinity have had limited success. While some salt-tolerant rice varieties have been developed, their yields in highly affected areas remain unsatisfactory. This necessitates innovative and sustainable strategies to protect our crops and ensure food security. Enter plant growth-promoting rhizobacteria (PGPR), a group of beneficial microorganisms that colonize plant roots and enhance plant growth through various mechanisms.

Recent research has highlighted the potential of PGPR in alleviating salt stress in rice seedlings. Specifically, ACC (1-aminocyclopropane-1-carboxylic acid) deaminase-producing bacteria have shown promise in reducing the harmful effects of ethylene, a stress hormone that inhibits plant growth under saline conditions. By modulating ethylene levels and providing other growth-promoting benefits, these bacteria offer a novel approach to improving rice production in salt-affected areas.

How Do ACC Deaminase-Producing Bacteria Help Rice Plants?

Rice seedlings enhanced by bacteria in a salt-affected field

ACC deaminase-producing bacteria utilize a fascinating mechanism to help plants cope with salt stress. When plants encounter high salt concentrations, they produce more ethylene, a stress hormone. While ethylene is involved in various plant processes, excessive amounts can hinder growth. These specialized bacteria contain an enzyme called ACC deaminase, which breaks down ACC, the immediate precursor to ethylene. This process effectively lowers ethylene levels in the plant, mitigating its inhibitory effects and allowing the plant to grow more vigorously.

The recent study isolated and characterized a salt-tolerant ACC deaminase-producing bacterium, Burkholderia sp. MTCC 12259, from a coastal rice field in Odisha, India. This strain, named P50, demonstrated remarkable ability to enhance rice seedling growth under salt stress. Researchers found that P50 not only reduces stress ethylene production but also exhibits several other beneficial traits:

Enhanced Production of Plant Hormones: P50 produces indole acetic acid (IAA), a plant hormone that promotes root development and overall growth.
Increased Exopolysaccharide (EPS) Production: EPS helps in binding with cations, decreasing the amount of available Na+ and providing enhanced salt tolerance in the plants.
Improved Proline Production: Proline acts as an osmoprotectant, helping plants maintain cellular water balance under saline conditions.

These combined effects enable rice seedlings to better withstand salt stress, resulting in improved growth, increased biomass, and enhanced tolerance to saline conditions. The P50 strain's ability to colonize root surfaces further supports its role in promoting plant health and resilience.

The Future of Sustainable Agriculture: Harnessing the Power of PGPR

The study highlights the potential of using salt-tolerant PGPR like Burkholderia sp. P50 as a sustainable approach to improving rice production in salt-affected regions. By reducing stress ethylene, enhancing nutrient availability, and promoting overall plant health, these bacteria offer a promising solution for ensuring food security in challenging environments. Further research and field trials are needed to fully explore the potential of PGPR and optimize their application in agriculture. However, the findings suggest that harnessing the power of these beneficial microorganisms could be a key strategy in building more resilient and sustainable agricultural systems.

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This article is based on research published under:

DOI-LINK: 10.1016/j.jplph.2018.10.010, Alternate LINK

Title: Enhancement Of Growth And Salt Tolerance Of Rice Seedlings By Acc Deaminase-Producing Burkholderia Sp. Mtcc 12259

Subject: Plant Science

Journal: Journal of Plant Physiology

Publisher: Elsevier BV

Authors: Anumita Sarkar, Krishnendu Pramanik, Soumik Mitra, Tithi Soren, Tushar Kanti Maiti

Published: 2018-12-01

Everything You Need To Know

How do plant growth-promoting rhizobacteria (PGPR) contribute to sustainable agriculture, especially in the context of rice production?

Plant growth-promoting rhizobacteria (PGPR) are beneficial microorganisms that colonize plant roots, improving plant growth through various mechanisms. ACC deaminase-producing bacteria, a subset of PGPR, help alleviate salt stress in rice by reducing the harmful effects of ethylene, a stress hormone. By modulating ethylene levels and providing other growth-promoting benefits such as enhanced production of plant hormones and increased exopolysaccharide production, these bacteria offer a novel approach to improving rice production in salt-affected areas. Further research is necessary to understand the full implications of PGPR. The impact of PGPR in combination with current methods of mitigating soil salinity also needs study.

What is the role of ACC deaminase in helping rice plants withstand salt stress?

ACC deaminase-producing bacteria contain an enzyme called ACC deaminase, which breaks down ACC (1-aminocyclopropane-1-carboxylic acid), the immediate precursor to ethylene. When plants are under salt stress, they produce ethylene, which can inhibit growth. By breaking down ACC, these bacteria lower ethylene levels in the plant, reducing its inhibitory effects and allowing the plant to grow more vigorously. Other factors such as proline production and the production of plant hormones also play a role.

What are the key characteristics of Burkholderia sp. MTCC 12259 (P50) that make it effective in promoting rice growth under saline conditions?

Burkholderia sp. MTCC 12259, also known as P50, is a salt-tolerant ACC deaminase-producing bacterium isolated from a coastal rice field in Odisha, India. It enhances rice seedling growth under salt stress by reducing stress ethylene production. Additionally, P50 produces indole acetic acid (IAA), a plant hormone that promotes root development, increases exopolysaccharide (EPS) production, which helps in binding with cations and improves proline production, an osmoprotectant that helps plants maintain cellular water balance under saline conditions.

What is the future potential for using PGPR, like Burkholderia sp. P50, to improve rice production in regions affected by soil salinity?

The use of salt-tolerant PGPR like Burkholderia sp. P50 represents a sustainable approach to improving rice production in salt-affected regions. These bacteria reduce stress ethylene, enhance nutrient availability, and promote overall plant health. This approach offers a promising solution for ensuring food security in challenging environments by building more resilient and sustainable agricultural systems. Further field trials are needed to fully explore the potential of PGPR and optimize their application.

Why is soil salinity a major threat to global food security, particularly for rice crops?

Soil salinity poses a significant threat to agriculture because high salt concentrations inhibit plant growth and reduce crop yields. The Food and Agricultural Organization (FAO) projects that soil salinity could devastate 50% of arable lands by 2050. Rice, a staple food for billions, is particularly vulnerable. Traditional methods of combating soil salinity have had limited success, making it necessary to explore innovative and sustainable strategies like the use of plant growth-promoting rhizobacteria (PGPR). The use of PGPR may offset some of the predicted impact of soil salinity.