Assessing the virulence of ophiostomatoid fungi associated with the pine-infesting weevils to scots pine Pinus sylvestris L. seedlings

The pine-infesting weevils are known to be effective vectors of ophiostomatoid fungi. To understand more about fungal virulence of these fungi, inoculation studies were conducted on Scots pine (<em>Pinus sylvestris</em> L.). Two-year-old seedlings were wound-inoculated with one of eleven ophiostomatoid fungi associated with pine-infesting weevils. After 11 weeks, a darkened lesion, extending from the point of inoculation, was observed in all species, except for <em>Ophiostoma</em> cf. <em>abietinum</em> Marm. &amp; Butin, <em>Ophiostoma quercus</em> (Georgev.) Nannf., and <em>Sporothrix inflata </em>de Hoog. Seedling mortality was observed in seedlings inoculated with <em>Leptographium truncatum</em> (M.J. Wingf. &amp; Marasas) M.J. Wingf., <em>Leptographium lundbergii</em> Lagerb. &amp; Melin<em>,</em> <em>Leptographium procerum</em> (W.B. Kendr.) M.J. Wingf., <em>Grosmannia radiaticola</em> (J.J. Kim, Seifert &amp; G.H. Kim) Zipfel, Z.W. de Beer &amp; M.J. Wingf., <em>Ophiostoma floccosum</em> Math.-Käärik,<em> Ophiostoma minus</em> (Hedgc.) Syd. &amp; P. Syd., and <em>Ophiostoma piliferum </em>(Fr.) Syd. &amp; P. Syd. <em>Ophiostoma minus</em> and <em>L. truncatum</em> caused the largest lesions and sapwood blue-stain in Scots pine. <em>Grosmannia radiaticola, Ophiostoma piceae </em>(Münch) Syd. &amp; P. Syd., <em>O. floccosum</em>,<em> O. piliferum,</em> <em>L. lundbergii</em>,and<em> L. procerum </em>produced significantly smaller lesions and sapwood blue-stain than <em>O. minus</em> and <em>L. truncatum</em>, while<em> O</em>. cf. <em>abietinum</em>, <em>O. quercus</em> and <em>S. inflata</em> did not cause any lesions.

Advances in understanding bioactivity of chitosan and chitosan oligomers against selected wood-inhabiting fungi

Nitrous acid deaminative depolymerisation was used to prepare three chitosan oligomer (CO) mixtures from high-molecular weight chitosan. These mixtures of chitosan oligosaccharides were analysed by electrospray ionisation mass spectroscopy, potentiometric titration and gel permeation chromatography. A method based on potentiometric titration of the amino groups of the oligomers gave an average degree of polymerisation (DP) for the three preparations of 5 (CODP5), 9 (CODP9) and 14 (CODP14). Chitosan acetate and the chitosan oligomer mixtures were assayed against Leptographium procerum, Sphaeropsis sapinea and Trichoderma harzianum on nutrient media. Leptographium procerum and S. sapinea growth was prevented by chitosan acetate and chitosan oligomers at concentrations of 0.3–0.4% (w/v), whereas T. harzianum was able to overcome the fungistatic action of these compounds. The oligomer preparation CODP14 exhibited superior specific activity to both CODP5 and chitosan acetate, suggesting an optimum molecular weight for bioactivity. All oligomer preparations were more effective at pH 4 than at pH 6. This result, in combination with the inactivity of N-acetylated CODP14, indicated that amino group protonation was an important factor for fungistatic activity. The CODP14 preparation was reduced with sodium borohydride and fractionated by alkali precipitation and ion exchange chromatography. Bioassays of these fractions pointed towards DP and degree of deacetylation (DD) as key factors in chito-oligosaccharide bioactivity. Conversely, the terminal aldehyde groups generated by depolymerisation did not contribute to the activity observed.

Ophiostomatoid fungi isolated from Pinus radiata logs imported from New Zealand to Korea

Ophiostomatoid fungi discolor lumber, logs, and tree sapwood. Stained wood has a lower market value and can be refused by importing customers because such products can potentially carry pathogenic fungi. Little information is available on the ophiostomatoid fungi that colonize Pinus radiata D. Don (radiata pine) logs imported from New Zealand into Korea. In this work, we attempted to identify the native and non-native fungi colonizing wood imported into Korea. At least 12 species of ophiostomatoid fungi, including an unknown Ophiostoma sp. A, were identified among the fungi-staining radiata pine. They were Leptographium procerum (Kendr.) Wingf., Leptographium bistatum Kim & Kim, Ophiostoma floccosum Mathiesen, Ophiostoma huntii (Rob.) Hoog & Scheff., Ophiostoma ips (Rumbold) Nannf., Ophiostoma nigrocarpum (David.) Hoog, Ophiostoma piceae (Münch) H. & P. Sydow, Ophiostoma piliferum (Fries) H. & P. Sydow, Ophiostoma quercus (Georgév.) Nannf., Ophiostoma radiaticola Kim et al., and Ophiostoma setosum Uzunovic et al. Of these species, O. floccosum was the dominant species in both logs and boards. We confirmed that many of the sapstain species that we isolated have been previously reported in Korea. However, four species, O. radiatcola, O. setosum, O. huntii, and O. nigrocarpum have not been reported previously in Korea. We also found the new species, L. bistatum, along with an unknown Ophiostoma sp. A.Key words: radiata pine, ophiostomatoid fungi, New Zealand, non-native organisms, β-tubulin gene.