Abstract

Forty-three endophytic fungal isolates were separated from the healthy twigs and barks of the hybrid poplar 'Neva' of Populus deltoides Marsh × Populus nigra L. Eleven distinct isolates were selected for further taxonomical identification by morphological traits and internal transcribed spacer (ITS) rRNA gene sequence analysis. Eight genera namely Alternaria, Aureobasidium, Botryosphaeria, Hyalodendriella, Mycosphaerella, Peyronellaea, Phoma and Valsa were identified on the basis of their morphological characterizations. Of them, the most frequent genus was Alternaria (that is, Ponipodef01, Ponipodef04 and Ponipodef07). Their ITS-rDNA sequences were compared with those available in the GenBank database to obtain the closest related species by BLAST analysis. A modified thin layer chromatography-bioautography assay was used to detect the antimicrobial activity of the n-butanol extracts of mycelia and culture filtrates of the isolates. Most of the fungal isolates were observed to have antibacterial activity, and antibacterial components mainly existed in mycelia. Two isolates Ponipodef05 and Ponipodef12 were also observed to have antifungal activity. The endophytic fungi isolated from the hybrid poplar 'Neva' of P. deltoides Marsh × P. nigra L. may be used as potential producers of antimicrobial natural products.

Key words: Poplar hybrid 'Neva', endophytic fungi, extract, antimicrobial activity.