[Isolation and Identification of the Plant Endophyte R-13 and Its Effect on Cadmium Accumulation in L].

The combination of endophytes and hyperaccumulator plants can significantly improve the efficiency of heavy metal phytoremediation in contaminated soil. A plant endophyte named R-13 was isolated from rice roots in a cadmium (Cd) contaminated paddy field. This strain exhibited a strong tolerance to Cd and could grow on a solid medium with a Cd concentration of 300 mg·kg. The R-13 strain was able to produce siderophores and Indole acetic acid (IAA), through color reactions. In addition, Pikovskaya's and Ashby's solid medium tests showed that the R-13 strain had a lower capacity for dissolving phosphorus but a higher capacity for fixing nitrogen. In the pot experiment, high-throughput sequencing technology was used to track the colonization of the R-13 strain in L. roots. Three days after inoculation, the relative abundance of in the root of L. had increased by 201.88% compared to the blank control (CK) and after two inoculations, the relative abundance of in the root of L. had increased by 1182.44% compared to CK. The relative abundance of in the root of L. began to decrease significantly from 5 days after inoculation. Inoculation with 20 mL·pot of R-13 fermentation broth resulted in no significant effects on the Cd content of roots, stems, leaves, or fruits of L. With 40 mL·pot of fermentation broth, the Cd content of vegetative organs and fruits was significantly increased. When it reached 200 mL·pot, the Cd content of vegetative organs was the highest, with Cd concentrations in the roots, stems, leaves, and fruits increasing by 84.42%, 43.67%, 64.06%, and 20.29%, respectively. In conclusion, root inoculation with endophytic R-13 can significantly increase the relative content of in the root system and enhance Cd absorption of L. Therefore, this strain has excellent prospects for application in the phytoremediation of soil contaminated with Cd.