Background and Aim:It is recently shown that ascomycetous fungi of Pezizomycotina endophytically associate with the healthy members of Cupressaceae (Coniferals). Research in our group has indicated that endophytic Alternaria species (Dothideomycetes) from Cupressaceae were highly bioactive. Here, we aimed at elucidating the possible biosynthetic pathways behind this bioactivity. Actually, we have already reported that some endophytic fungi of yew trees (Taxus baccata) were capable of producing taxane diterpenoids. Methods:Genomic DNAs from eight endophytic Alternaria isolates from Iranian endemic Cupressaceae were subjected to PCR analyses to screen for the presence of taxadine synthase (TS), 10-deacetylbaccatin III-10-O-acetyl transferase (DBAT) and C-13 phenylpropanoid side chain-CoA acyltransferase (BAPT) genes in the taxol biosynthetic pathway. Results:Out of 8 isolates, 6 gave positive results for the presence of all three genes, i.e. TS, DBAT and BAPT genes. The other 2 isolates gave positive results only for DBAT and BAPT genes. This indicates the presence of taxane diterpenoid biosynthesis pathway in endophytic Alternaria fungi of Cupressaceae. Indeed, DBAT catalyzes the formation of baccatin III, which is the immediate diterpenoid precursor of taxol. BAPT catalyzes the selective 13-O-acylation of baccatin III with b-phenylalanoyl-CoA as the acyl donor to form N-debenzoyl-20-deoxytaxol, i.e. it catalyzes the attachment of the biologically important taxol side chain precursor. Conclusion:One of the mechanisms employed by endophytic Alternaria species of Cupressaceae to live in niches occupied by antagonistic microorganisms could be the production of taxane diterpenoids. This is the first to introduce the Alternaria species of Cupressaceae as the potential producers of paclitaxel (Taxol).
