Comparative Effects of Individual and Consortia Plant Growth Promoting Bacteria on Physiological and Enzymatic Mechanisms to Confer Drought Tolerance in Maize (Zea mays L.)

Abstract

Mitigation strategies based on plant–microbe interactions to increase the performance of plants under water-deficit conditions are well documented. However, little is known about a suitable consortium of bacterial inoculants and underlying physiological and enzymatic events to improve drought tolerance in maize. We performed laboratory and pot experiments to understand the synergistic interactions among plant growth-promoting bacteria to alleviate the drought-induced damages in maize. Initially, ten bacterial strains were evaluated for their osmotic stress tolerance capacity by growing them in a media containing 0, 10, 20, and 30% polyethylene glycol (PEG-6000). Also, the seeds of a drought tolerant (NK-6654) and sensitive (SD-626) maize cultivar were inoculated with these bacterial strains in the first pot experiment to determine their effects on the growth and physiological processes. Later, in the second pot experiment, the best performing inoculants were selected to study the individual and synergistic effects of bacterial inoculation to confer drought tolerance in maize. Our findings showed that the inoculation with tolerant strains resulted in higher photosynthetic activity (25–39%), maintenance of leaf water status (14–18%) and pigments (27–32%), and stimulation of antioxidant machinery (28–38%) than no inoculation in water-stressed maize seedlings. Moreover, the treatment with bacteria consortia further stimulated the drought protective mechanisms and resulted in higher efficiency of photosynthetic (47–61%) and antioxidant systems (42–62%) than the individual inoculants under water-deficit conditions. We conclude that the inoculation with microbial consortia regulates water uptake, photosynthetic performance, and stress metabolites to minimize drought-induced damages in maize.

Bioformulations Derived from <i>Enterobacter</i> sp. NRRU-N13 and Oligochitosan Alleviate Drought Stress in Thai Jasmine Rice (<i>Oryza sativa</i> L. var. KDML105)

“… Abdelaal et al (2021) reported similar findings, indicating that the application of chitosan significantly decreased electrolyte leakage. Furthermore, PGPR has been shown to reduce electrolyte leakage in drought-stressed plants ( Saleem et al , 2021 ). Synergistic combinations may improve drought tolerance in rice plants by reducing proline accumulation and electrolyte leakage while concurrently increasing the activities of antioxidant enzymes as well as chlo­rophyll and relative water contents.…”

Influence of Soil Phosphate on Rhizobacterial Performance in Affecting Wheat Yield

“…The positive effects of PGPR on plant health have been well documented in literature; however, the inherent complexity of PGPR interactions with the environment, native flora, and crop-specific conditions contributes to inconsistent outcomes [ 46 , 47 ]. To address these challenges, contemporary research efforts increasingly focus on the use of specific combinations of PGPR [ 23 , 48 – 50 ] with a wide spectrum of modes of action, that is sufficiently robust to counter environmental factors, [ 49 , 51 ]. For instance, recent studies by Calvo et al [ 52 ] have highlighted the efficacy of tailored PGPR blends in enhancing nutrient uptake and stress tolerance in various crop species.…”

Two human milk–like synthetic bacterial communities displayed contrasted impacts on barrier and immune responses in an intestinal quadricellular model

“…These differences suggest that the final properties of the SynComs were not strictly the sum of effects of the strains composing it. The assembly of strains can confer new functionalities, as shown in plant studies where bacterial consortia increased photosynthetic and antioxidant systems compared to individual bacteria [ 54 , 55 ]. Conversely, the assembly of strains may lead to a loss of functions.…”