Exploring the potential of seed inoculation with microbial consortia to mitigate drought stress in maize plants under greenhouse conditions

Background and aimsPlant-beneficial microbes may attenuate climate change-induced stresses on plants such as drought. We investigated the potential of beneficial microbial consortia (BMc) on plant growth and rhizosphere bacterial/archaeal community under drought.MethodsSeeds of Zea mays B73 were inoculated with six plant-beneficial bacterial isolates either alone or combined in two three-member consortia (BMc1, BMc2) before sowing in loamy or sandy substrates in the greenhouse. A known effective consortium (BMc3) was included as positive control. Drought treatment was established with the BMc treatments by omitting watering in the last of the five weeks growth period. The maize growth in single and BMc treatments was determined. Colony-forming units (CFUs) of inoculants were evaluated by selective plating, and effects of BMc treatments on the native rhizosphere bacterial/archaeal community were assessed using 16S rRNA gene amplicon sequencing of basal root and root tip rhizosphere of plants grown in loam.ResultsIn both substrates and water conditions, CFUs of single and BMc inoculations were higher at rhizosphere basal roots than root tips. Under well-watered conditions, seed inoculation with a single bacterial isolate had no effect on maize growth in both substrates. BMc treatment resulted in higher shoot (but not root) growth compared to non-inoculated controls in both water conditions in loam. The root zone was the most important driver for bacterial/archaeal beta-diversity, followed by water conditions, while BMc treatments showed no effect.ConclusionOur study suggests that BMc seed inoculation has the potential to attenuate drought stress during maize growth.