Introducing Alternaria tenuissima SBUp1, as an endophytic fungus of Ferula assa-foetida from Iran, which is a rich source of rosmarinic acid

Endophytic fungi are the endogenous micro-organisms to interacting with the plant cells, which do not exhibit any symptoms on the host plant and may produce some of the main secondary metabolites of the host plant cells. Ferula assa-foetida is a perennial and endemic medicinal plant of Iran, which is a rich source of sesquiterpene, coumarins, polysulfides and phenolic acids. In this study, 28 endophytic fungi isolates including Fusarium (60·7%), Aspergillus (7·1%), Alternaria (17·9%) and Plectosphaerella (7·1%) were isolated from F. assa-foetida root (57·1%), stem (32·1%) and leaf (10·8%) collected from Parvand protected area. Subsequently, their ability to produce phenolic acids was evaluated. The high amounts of total phenol (326·09 mg g^-1 of dry weight, DW), total flavonoid (901·11 mg g^-1 DW) and antioxidant activity (247·96 mg l^-1 ) were found in the supernatant fluid of SBUp1 isolate. The high-performance liquid chromatography analysis of 14 phenolic acids showed that rosmarinic acid (RA) is the main phenolic acid in the supernatant fluid of SBUp1 by 64·11 mg g^-1 DW confirmed by the liquid chromatography coupled with mass spectrometric analysis. According to morphological identification followed by phylogenetic study based on internal transcribed spacer (ITS) sequencing (ITS1-5.8S-ITS2) analysis, the SBUp1 isolate was identified as Alternaria tenuissima. Eventually, to our knowledge, it is the first document confirming A. tenuissima as an endophytic fungus of F. assa-foetida, which is a rich source of RA.