AUTHOR=Ali Baber , Hafeez Aqsa , Ahmad Saliha , Javed Muhammad Ammar , Sumaira  , Afridi Muhammad Siddique , Dawoud Turki M. , Almaary Khalid S. , Muresan Crina Carmen , Marc Romina Alina , Alkhalifah Dalal Hussien M. , Selim Samy 

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.921668

DOI=10.3389/fpls.2022.921668

ISSN=1664-462X

ABSTRACT=<p>Soil salinity is the major abiotic stress that disrupts nutrient uptake, hinders plant growth, and threatens agricultural production. Plant growth-promoting rhizobacteria (PGPR) are the most promising eco-friendly beneficial microorganisms that can be used to improve plant responses against biotic and abiotic stresses. In this study, a previously identified <italic>B. thuringiensis</italic> PM25 showed tolerance to salinity stress up to 3 M NaCl. The Halo-tolerant <italic>Bacillus thuringiensis</italic> PM25 demonstrated distinct salinity tolerance and enhance plant growth-promoting activities under salinity stress. Antibiotic-resistant Iturin C (<italic>ItuC</italic>) and bio-surfactant-producing (<italic>sfp</italic> and <italic>srfAA</italic>) genes that confer biotic and abiotic stresses were also amplified in <italic>B. thuringiensis</italic> PM25. Under salinity stress, the physiological and molecular processes were followed by the over-expression of stress-related genes (APX and SOD) in <italic>B. thuringiensis</italic> PM25. The results detected that <italic>B. thuringiensis</italic> PM25 inoculation substantially improved phenotypic traits, chlorophyll content, radical scavenging capability, and relative water content under salinity stress. Under salinity stress, the inoculation of <italic>B. thuringiensis</italic> PM25 significantly increased antioxidant enzyme levels in inoculated maize as compared to uninoculated plants. In addition, <italic>B. thuringiensis</italic> PM25-inoculation dramatically increased soluble sugars, proteins, total phenols, and flavonoids in maize as compared to uninoculated plants. The inoculation of <italic>B. thuringiensis</italic> PM25 significantly reduced oxidative burst in inoculated maize under salinity stress, compared to uninoculated plants. Furthermore, <italic>B. thuringiensis</italic> PM25-inoculated plants had higher levels of compatible solutes than uninoculated controls. The current results demonstrated that <italic>B. thuringiensis</italic> PM25 plays an important role in reducing salinity stress by influencing antioxidant defense systems and abiotic stress-related genes. These findings also suggest that multi-stress tolerant <italic>B. thuringiensis</italic> PM25 could enhance plant growth by mitigating salt stress, which might be used as an innovative tool for enhancing plant yield and productivity.</p>