Sammendrag
The morphological variation, secondary metabolite profiles and restriction fragment length polymorphisms (RFLPs) of PCR
amplified intergenic spacer (IGS) ribosomal DNA (rDNA) were studied in 27 isolates of Fusarium equiseti, 25 isolated from
Norwegian cereals and 2 from soil obtained from the IBT culture collection (BioCentrum, Technical University of Denmark).
All 27 isolates were tested for production of fusarochromanone (FUSCHR), zearalenone (ZEA) and the trichothecenes: 15-
monoacetoxy-scirpentriol (MAS), diacetoxy-scirpenol (DAS), T-2 and HT-2 toxins, T2-triol, neosolaniol (NEO), deoxynivalenol
(DON), nivalenol (NIV) and 4-acetylnivalenol (Fus-X). The trichothecenes were analysed by GC-MS in a selected ion
monitoring mode, while FUSCHR was determined by ion pair HPLC with fluorometric detection and production of ZEA by
TLC. For amplification of IGS rDNA primers CNL12 and CNS1 were applied. IGS rDNA was digested with the four restriction
enzymes: AvaII, CfoI, EcoRI and Sau3A. In addition, we sequenced the IGS rDNA region of three of the Norwegian isolates.
There were two morphological types among the Norwegian strains of F. equiseti, type I with short apical cells (dominating) and
type II with long apical cells, with four haplotypes identified based on the RFLP data. Variation in secondary metabolite profiles
within and between the morphological groups was observed and the levels of produced toxins were: FUSCHR 3000–42,500
and 25–30 ng/g, NIV 20–2500 and 120–700 ng/g, FUS-X 20–15,000 and 0 ng/g, DAS 30–7500 and 0–600 ng/g, and MAS 10–
600 and 0–500 ng/g, for strains with short and long apical cells, respectively. NEO was detected in 16/27 strains tested (all
morphotype I). All but four strains of type I (these four lacked a restriction site for EcoRI) had identical RFLP profiles. The
isolates of type II had two haplotypes. The IGS sequence similarity data indicated differences between these morphotypes
corresponding to two separate lineages apparently at the species level.
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