Isolation and identification of fungal strains producing gibberellins from the root of plants

249 fungal strains were isolated from the roots of 26 plants, and the production of GAs was spectrophotometrically examined. As a result 76 fungal strains were shown to produce GAs. Bioassay of culture broth from seventy six fungal strains producing GAs was carried out with waito-c rice, that is dwarf rice. The seventy six fungi with GAs-producing activity were incubated for seven days in 40 mL of Czapek's liquid medium at 30°C and 180 rpm, and the culture broth of fungi were treated on the 2-leaf rice sprout. Fifteen of these showed plant growth promoting activity and the amount of each GAs in the medium was measured by Gas chromatography-mass spectrometer (GC-MS). Nine of these fungi were also identified by genetic analysis of the nucleotide sequences in the internal transcribed spacer region of the ribosomal DNA.