Endophytic Klebsiella sp. San01 promotes growth performance and induces salinity and drought tolerance in sweet potato (Ipomoea batatas L.)

Endophytic plant-growth-promoting bacteria help plants to cope with severe environmental stresses. A Klebsiella sp. strain San01 isolated from sweet potato roots exhibited diverse plant-growth-promoting activities, including indole acetic acid production, ammonia production, and phosphate solubilization. San01 inoculation significantly increased the growth characteristics of sweet potato. Moreover, the sweet potato inoculated with San01 resulted in the alleviation of drought and salinity stresses. In comparison with the non-inoculated plants, the wilting symptom and the inhibition of photochemical response were significantly diminished in San01-inoculated plants under stress conditions. In the presence of San01, the enhancement of 2,2-diphenyl-1-picrylhydrazyl radical scavenging ability and elevated activities of ascorbate peroxidase and superoxide dismutase were observed to combat the oxidative stress in sweet potato. Further investigation showed that the San01 inoculation enhanced the expression of the IbLEA gene in sweet potato under salinity and drought. These results confer a promising biotechnological approach through San01 interaction to develop stress-tolerant sweet potato plants.