Optimized drought tolerance in barley (Hordeum vulgare L.) using plant growth-promoting rhizobacteria (PGPR)

Abstract

Barley is among the most cultivated cereals in areas suffering water deficit, which impacts their growth and crop production. Here, we aimed to select plant growth-promoting rhizobacteria (PGPR) that have the potential to enhance barley growth under drought stress. Thus, 15 bacterial isolates were selected for drought tolerance (more than −0.49 MPa) and screened for PGP characteristics: phosphate solubilization, production of exopolysaccharides, hydrogen cyanide, ammonia, siderophores, and indole-3-acetic acid, and enzyme activities such as phosphatase, cellulase, pectinase, and chitinase. The top four isolates (MFC1, MFE3, MFF2, and MFF5) regarding PGP traits were tested on barley plants in irrigated and under drought conditions. The inoculation of barley plants by the isolates increased the indexes of plant tolerance to drought stress, such as shoot dry weight, relative water content, chlorophyll pigments content, photosynthesis efficiency (Fv/m ratio), and proline content. On the other hand, plant sensitivity indexes such as electrolytes leakage and MDA and hydrogen peroxide contents were decreased. Principal component analysis discriminates clearly between uninoculated and inoculated plants. This isolate was identified as Providencia rettgeri. Indeed, under stressful conditions, MFE3 showed high plant tolerance index values, making it a potent isolate. Our current study showed that the interaction between barley plants and MFE3 might lead to an effective plant-bacteria system under drought stress.