Bacillus mycoides PM35 Reinforces Photosynthetic Efficiency, Antioxidant Defense, Expression of Stress-Responsive Genes, and Ameliorates the Effects of Salinity Stress in Maize

Abstract

Soil salinity is one of the abiotic constraints that imbalance nutrient acquisition, hampers plant growth, and leads to potential loss in agricultural productivity. Salt-tolerant plant growth-promoting rhizobacteria (PGPR) can alleviate the adverse impacts of salt stress by mediating molecular, biochemical, and physiological status. In the present study, the bacterium Bacillus mycoides PM35 showed resistance up to 3 M NaCl stress and exhibited plant growth-promoting features. Under salinity stress, the halo-tolerant bacterium B. mycoides PM35 showed significant plant growth-promoting traits, such as the production of indole acetic acid, siderophore, ACC deaminase, and exopolysaccharides. Inoculation of B. mycoides PM35 alleviated salt stress in plants and enhanced shoot and root length under salinity stress (0, 300, 600, and 900 mM). The B. mycoides PM35 alleviated salinity stress by enhancing the photosynthetic pigments, carotenoids, radical scavenging capacity, soluble sugars, and protein content in inoculated maize plants compared to non-inoculated plants. In addition, B. mycoides PM35 significantly boosted antioxidant activities, relative water content, flavonoid, phenolic content, and osmolytes while reducing electrolyte leakage, H2O2, and MDA in maize compared to control plants. Genes conferring abiotic stress tolerance (CzcD, sfp, and srfAA genes) were amplified in B. mycoides PM35. Moreover, all reactions are accompanied by the upregulation of stress-related genes (APX and SOD). Our study reveals that B. mycoides PM35 is capable of promoting plant growth and increasing agricultural productivity.

Effect of Jasmonic Acid Foliar Spray on the Morpho-Physiological Mechanism of Salt Stress Tolerance in Two Soybean Varieties (Glycine max L.)

“…Among the treatment groups, exogenous JA application with salt stress improved photosynthetic pigments in comparison with salt stress alone. These findings are supported by previous studies, indicating that exogenous JA application can improve the photosynthetic pigments under salinity conditions [21,37,39,44,52,53]. Possibly, the increased content of chlorophyll pigments was caused by the improved activity of enzymes that are involved in the biosynthesis of chlorophyll, such as protochlorophyllide reductase and α-aminolevulinic acid dehydratase [54][55][56].…”

“…Salinity is a major abiotic stress factor that adversely affects seed germination, plant growth, and productivity [35][36][37]. The phytohormone jasmonic acid (JA) can influence plant growth and development and regulates plant responses to biotic and abiotic factors [23,[38][39][40][41][42][43].…”

Bacillus thuringiensis PM25 ameliorates oxidative damage of salinity stress in maize via regulating growth, leaf pigments, antioxidant defense system, and stress responsive gene expression

“…The Exopolysaccharides quantification assay was performed following the method described by Ali et al ( 2022a ). The strain B. thuringiensis PM25 was grown in 50 ml ATCC no.…”

Managing Phosphorus Availability from Organic and Inorganic Sources for Optimum Wheat Production in Calcareous Soils

“…Soil pH and EC were measured by adopting the protocol described by [13,14], respectively. The soil samples were also analyzed for texture [15], lime [16] and AB-DTPA extractable P [17] at the heading and post-harvest stages.…”