Gibberellin A7 production by Aspergillus tubingensis YH103 and cultural characteristics of endophytic fungi isolated from Tetragonia tetragonoides in Dokdo islands

Coastal plant species Tetragonia tetragonoides (Pall.) Kuntze native to the Dokdo islands was sampled and then 17 endophytic fungi were purely isolated based on morphological differences. The fungal isolates were characterized by their growth properties under NaCl concentration or pH gradient. Culture filtrates of the 17 fungal isolates were treated to Waito-c rice (WR) seedlings for verifying plant growth-promoting activity. As the results, YH103 strain showed the highest plant growth-promoting activity among them. Phylogenetic analysis of the isolates was done by the maximum likelihood method based on partial internal transcribed spacer region (ITS region: Contaning ITS1, 5.8S, and ITS2), beta-tubulin (BenA), and calmodulin (CaM) gene sequences. Chromatographic analysis of the strain YH103 culture filtrate showed the existence of gibberellins (GA₄, GA₇, GA₈, and GA₁₉). Finally, the strain YH103 was identified as Aspergillus tubingensis by microscopic observation and molecular analysis and, to our knowledge, this is the first report of GAs producing A. tubingensis.