Oosporein Produced by Root Endophytic Chaetomium cupreum Promotes the Growth of Host Plant, Miscanthus sinensis, under Aluminum Stress at the Appropriate Concentration

Chaetomium cupreum, a root endophyte in Miscanthus sinensis, enhances Al tolerance in M. sinensis by changing aluminum (Al) localization and the production of a siderophore, oosporein, which chelates Al for detoxification. Oosporein has various functions, including insecticidal activity, phytotoxicity, antifungal activity, and a siderophore. In our study, we focused on the detoxification effect of oosporein as a siderophore and on the growth of M. sinensis under Al exposure. In addition, the phytotoxicity of oosporein to M. sinensis was confirmed to compare with those in Lactuca sativa and Oryza sativa as control plants. Under Al stress, oosporein promoted plant growth in M. sinensis seedlings at 10 ppm, which was the same concentration as that detected in M. sinensis roots infected with C. cupreum in our previous study. Oosporein also showed low phytotoxicity to M. sinensis compared with L. sativa at even high concentrations of oosporein. These results suggest that the concentration of oosporein in M. sinensis roots would be maintained at the appropriate concentration to detoxify Al and would promote M. sinensis growth under Al stress, although oosporein would show low phytotoxicity to the natural host plant, M. sinensis, compared with the non-host plant, L. sativa.