Durum wheat (Triticum durum Desf.) is one of the most widely grown crops in Italy, extending to approximately 1.5 million ha. Seedborne fungi, affecting both germination and commercial quality of the product, represent a threat to wheat production. Several Fusarium species produce mycotoxins, secondary metabolites harmful to humans and animals. In 2006, monitoring the health status of durum wheat kernels from central (Pollenza, MC) and southern Italy (Foggia; Gravina di Puglia, BA; Enna) was conducted. Kernels at the 11.3 Feeke's scale growth stage were analyzed with the deep freezing blotter test (1). Ten isolates morphologically similar to Fusarium poae were observed. For identification, monosporic isolates were transferred onto potato dextrose agar (PDA) and carnation leaf agar (CLA) to grow at 23°C with exposure to 12-h alternate cycles of darkness and near-UV light (Philips TLD 18W/08 Blacklight Blue Fluorescent Lamp, peak 360 nm). The shape and dimension of microconidia were similar to those of F. poae. The average radial daily growth rate (4.7 ± 1.0 mm day--1) of seven isolates at 23°C was significantly different (P < 0.05) from those of F. poae (8.8 ± 0.2 mm day--1) and F. sporotrichioides (9.4 ± 0.3 mm day--1). In addition to a slower growth rate, these isolates differed from F. poae because of a powdery appearance on PDA, the presence of polyphialides, the absence of macroconidia, and the lack of the peach-like odor. On the basis of the characters observed, the fungus was identified as F. langsethiae, a species recently described from several grains, including wheat (2). To confirm the diagnosis, the internal transcribed spacer (ITS) region of four isolates (ISPaVe ER-1399, ER-1400, ER-1401, and ER-1402) was amplified using universal primers ITS4 and ITS5 (3). The 546-bp product obtained was directly sequenced at the GenLab, Enea, Rome. A homology search using the BLASTn algorithm of all obtained sequences showed 100% identity with GenBank sequence AY680864, corresponding to F. langsethiae. One of these sequences (ISPaVe ER-1400) was deposited in GenBank with Accession No. EF526078. The DNAs of four isolates of F. langsethiae and one each of F. poae and F. sporotrichioides were amplified with the F. langsethiae-specific primers FlangF3 and LanspoR1 (4). The PCR conditions consisted of the initial denaturation at 94°C for 2 min, 35 cycles each of 30 sec at 94°C, 30 sec at 58°C, 1 min at 72°C, and a final extension at 72°C for 7 min. No amplification was obtained from F. poae and F. sporotrichioides, while a PCR product of the expected size (310 bp) was obtained from all F. langsethiae isolates, confirming their specific identification. To our knowledge, this is the first report of F. langsethiae on durum wheat in Italy. This species is known to produce the T2 and HT2 toxins, type A trichotecenes related to alimentary toxic aleukia in humans and haematotoxicity and immunotoxiciticy in animals. A large-scale monitoring of this fungus on durum wheat in Italy is in progress.
References: (1) T. Limonard. Neth. J. Plant Pathol. 72:319, 1966. (2) M. Torp and H. I. Nirenberg. Int. J. Food Microbiol. 95:247, 2004. (3) T. J. White et al. Page 315 in: PCR Protocols, a Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (4) A. Wilson et al. FEMS Microbiol. Lett. 233:69, 2004.
