REVIEW PAPER
Exopolysaccharide-Producing PGPR: Mechanisms
for Alleviating Salinity-Induced Plant Stress
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Department of Biology, College of Science in Zulfi, Majmaah University, Al-Majmaah 11952, Saudi Arabia
Submission date: 2024-09-06
Final revision date: 2024-10-16
Acceptance date: 2024-12-02
Online publication date: 2025-03-27
Corresponding author
Wardah A. Alhoqail
Department of Biology, College of Science in Zulfi,, Majmaah University, Al-Majmaah Saudi Arabia., 11952, Al-Majmaah, Saudi Arabia
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ABSTRACT
Elevated salinity levels pose a significant challenge to global crop production, affecting approximately
85% of the Earth’s arable land. The stress induces disruptions in vegetative development and yield by
inducing osmotic imbalance, toxicity from ions, and membrane instabilities, ensuing in a substantial
fall in crop production. However, the administration of EPS-producing bacteria promises an optimistic
approach that can minimize the effects of salinity and boost crop resistance in saline conditions. EPSproducing
bacteria have a dynamic role in reducing the harmful effects of salt stress through several
mechanisms, such as restricting the absorption of sodium, improving the intake of beneficial ions such
as K+, Ca2+, Mg2+, and P, elevating levels of antioxidants, and encouraging the establishment of soil
aggregates. These bacteria assist in regulating ion balance in plant cells experiencing salt stress, hence
improving plant development traits and stress tolerance. When the level of salt elevates in the soil, these
bacterial strains form a protective layer (biofilm) around roots and prevent the uptake of sodium ions
into the plant. EPS also forms complexes with sodium ions in the soil, so decreasing their accessibility
for plant uptake and contributing to the maintenance of an ideal ion equilibrium for plant survival.
In addition, bacteria that produce EPS enhance soil structure and fertility by promoting soil aggregation,
enhancing nutrient availability, and improving water retention capacity. EPS-producing bacteria have
a crucial role in enhancing the health and productivity of plants cultivated in saline environments.
In addition, bacteria that produce EPS show positive impacts on the efficiency of photosynthesis,
the amount of water in plants, and markers of oxidative stress in plants that are exposed to salt
stress. These bacteria improve photosynthetic rates by enhancing food availability and water uptake
in the rhizosphere, resulting in higher chlorophyll production and overall plant development.
Furthermore, bacteria that produce EPS increase the water content in plant tissues, resulting in better
hydration and overall plant health. Furthermore, these bacteria reduce levels of oxidative stress markers
such as malondialdehyde (MDA) and hydrogen peroxide (H2O2), therefore increasing antioxidant
defenses and reducing oxidative damage in plants subjected to salt stress.