PGPR regulate caspase-like activity, programmed cell death, and antioxidant enzyme activity in paddy under salinity

Area of Science:

• Agricultural Science
• Plant Biology
• Microbiology

Background:

• Salinity stress negatively impacts the growth of salt-sensitive rice cultivars.
• Plant growth-promoting rhizobacteria (PGPR) are known to mitigate adverse environmental conditions for plants.

Purpose of the Study:

• To investigate the protective effects of Pseudomonas pseudoalcaligenes and Bacillus pumilus against salinity stress in rice.
• To understand the mechanisms by which PGPR enhance salt tolerance in rice plants.

Main Methods:

• Controlled environmental growth conditions were used to study rice GJ17 cultivar responses.
• Inoculation with specific root-associated bacteria (Pseudomonas pseudoalcaligenes and Bacillus pumilus).
• Assessment of physiological parameters including lipid peroxidation, superoxide dismutase activity, cell membrane integrity, and programmed cell death.

Main Results:

• PGPR inoculation significantly reduced harmful effects of salinity on the salt-sensitive rice GJ17 cultivar.
• Reduced lipid peroxidation and superoxide dismutase activity were observed in inoculated plants under salt stress.
• PGPR mitigated reactive oxygen species toxicity, decreasing cell caspase-like protease activity and programmed cell death, thereby increasing cell viability.

Conclusions:

• Root-associated bacteria Pseudomonas pseudoalcaligenes and Bacillus pumilus confer significant salt tolerance to rice.
• PGPR enhance plant adaptation to salt stress by reducing oxidative damage and programmed cell death.
• Inoculation with these PGPR strains can alleviate up to 1.5% salinity stress, improving rice plant tolerance and viability.