Increased drought stress resilience of maize through endophytic colonization by Burkholderia phytofirmans PsJN and Enterobacter sp. FD17

Drought is one of the major environmental stresses that adversely affects crop growth and productivity worldwide. The effect of inoculation of two bacterial endophytes Burkholderia phytofirmans strain PsJN and Enterobacter sp. FD17 on growth, water status and photosynthetic activity of two maize cultivars under drought stress conditions was investigated. Plants were exposed to drought stress by withholding irrigation at vegetative growth stage (45 days after planting). The inoculant strains efficiently colonized maize seedlings and were recovered from root, shoot and leaves of both irrigated and stressed plants. Drought stress had drastic effects on growth, leaf water content and photosynthesis of maize seedlings. Our results revealed that bacterial inoculation minimized the drought stress-imposed effects significantly increasing shoot biomass, root biomass, leaf area, chlorophyll content, photosynthesis, and photochemical efficiency of PSII. Similarly, bacterized seedlings showed higher leaf relative water content (30%) compared to control, whereas 43% higher leaf damage in terms of relative membrane permeability was observed in non-inoculated plants under drought stress. Strain PsJN was more efficient than FD17 in terms of influencing growth and physiological status of the seedlings under drought stress. Our data suggest that maize plants can be protected from inhibitory effects of the drought stress by the harbored bacterial endophytes, although the degree of protection depends on the type of the bacterial strain and the plant genotype.