Complete genome sequence of Sphingomonas sp. Cra20, a drought resistant and plant growth promoting rhizobacteria.

Sphingomonas sp. Cra20 is a rhizobacteria isolated from the root surface of Leontopodium leontopodioides in the Tianshan Mountains of China and was found to influence root system architecture. We analyzed its ability for plant-growth promotion and the molecular mechanism involved by combining the physiological and genome information. The results indicated that the bacterium enhanced the drought resistance of Arabidopsis thaliana and promoted growth mainly through the strain-released volatile organic compounds. The genome consisted of one circular chromosome and one circular plasmid, containing a series of genes related to the plant-growth promotion. Furthermore, multiple copies of cold-associated genes, general stress response genes, oxidative stress genes and DNA repair mechanisms supported its survivability in extreme environments. In addition, the strain had the ability to degrade xylene and 2, 4-D via a variety of monooxygenases and dioxygenases. This provides further information and will promote the application of Cra20 as a biofertilizer in agriculture.