Mitigation of Salt Stress in Zea mays L. through Halo Tolerant Endophytic Bacteria Isolated from Silybum marlanu

Abstract

Salinity is one of the major abiotic stress. Soil with high salt content can negatively impact plant growth and agricultural producti vity by hindering the ability of plants to acquire nutrients. Under elevated salinity stress, agricultural production is greatl y reduced due to impaired plant nutrition, hormonal imbalance, production of reactive oxygen species, osmotic stress, and ion toxicity. The halo-tolerant varieties and conventional agricultural practices might not be sufficient for desired crop yield to fulfill increased food demands. Medicinal plants harbor certain halo-tolerant and plant growth-promoting microbes that can assist plants to withstand drastic salinity stress. This study found that certain halo-tolerant plant PGP endophytic bacteria can mitigate the deleterious effects of soil salinity on plant development, growth and agricultural productivity. Two specific strains (B-1 and B-2) were found to be tolerant to salt concentrations up to 3 M NaCI and exhibited PGP traits such as the production of Ammonia, Hydrogen cyanide, exopolysaccharides, and Indole-3-acetic acid as well as nitrogen fixation properties under salinity stress. In a pot experiment, inoculation of these halo-tolerant PGPB improved growth, biomass, and agro-morphological traits in maize plants under NaCl stress (0-900 mM NaCI). In comparison to the un-inoculated control, B-1 performed better than B-2 in terms of shoot length, fresh weight, root length, dry weight, plant height, leaf surface area, photosynthetic pigments, and relati ve water content. PGPB-inoculated plants under saline conditions also had considerably higher levels of antioxidant enzymes and flavonoid s. According to the study, PGPB-inoculation may be an environmentally beneficial way to treat salinity stress for sustainable agriculture.