Pantoea alhagi, a novel endophytic bacterium with ability to improve growth and drought tolerance in wheat.

A novel strain LTYR-11ZT that exhibited multiple plant growth promoting (PGP) traits was isolated from the surface-sterilized leaves of Alhagi sparsifolia Shap. (Leguminosae), which reprsents one of the top drought tolerant plants in north-west China. Phylogenetic analysis of 16S rRNA gene sequences and multilocus sequence analysis based on partial sequences of atpD, gyrB, infB and rpoB genes revealed that strain LTYR-11ZT was a member of the genus Pantoea, with Pantoea theicola NBRC 110557T and Pantoea intestinalis DSM 28113T as the closest phylogenetic relatives. The results of DNA-DNA hybridization, phenotypic tests and fatty acid analysis confirmed that strain LTYR-11ZT represents a novel species of the genus Pantoea, for which we propose the name Pantoea alhagi sp. nov. Confocal microscopy observation revealed that strain LTYR-11ZT effectively colonizes the rhizoplane of both Arabidopsis and wheat. Strain LTYR-11ZT was able to promote the growth of wheat enhancing its resistance to drought stress. Strain LTYR-11ZT led to increased accumulation of soluble sugars, decreased accumulation of proline and malondialdehyde (MDA), and decreased degradation of chlorophyll in leaves of drought-stressed wheat. Our findings will contribute to the development of a novel biotechnological agent to improve the adaptation of crop plants to drought in arid ecosystems.