The newly isolated endophytic fungus Paraconiothyrium sp. LK1 produces ascotoxin.

We have isolated five endophytic fungi from the roots of Capsicum annuum, Cucumis sativus and Glycine max. The culture filtrates (CF) of these endophytes were screened on dwarf mutant rice (Waito-C) and normal rice (Dongjin-byeo). Endophyte CAC-1A significantly inhibited the growth of Waito-C and Dongjin-byeo. Endophyte CAC-1A was identified as Paraconiothyrium sp. by sequencing the ITS rDNA region and phylogenetic analysis. The ethyl acetate fraction of Paraconiothyrium sp. suppressed the germination of Lactuca sativa and Echinochloa crus-galli seeds. The ethyl acetate fraction of the endophyte was subjected to bioassay-guided isolation and we obtained the phytotoxic compound ascotoxin (1) which was characterized through NMR and GC/MS techniques. Ascotoxin revealed 100% inhibitory effects on seed germination of Echinochloa crus-galli. Compound (1) was isolated for the first time from Paraconiothyrium sp.