Effect of growth conditions on Ophiostoma piceae (Münch) H. & P. Syd. and Ophiostoma floccosum Math-Käärik albino strains culture morphology

Blue stain in Pinus radiata D. Don wood is predominantly caused by Ophiostoma genus fungi. Stained wood causes significant economic losses to forestry and timber industries. Currently, different chemical fungicides are used to prevent the occurrence of blue stain fungi. However, recent reports have questioned the environmental friendliness of these fungicides. For this reason, the use of biological control, in particular with albino strains of the Ophiostoma genus, appears to be an environmentally safe and a technically feasible alternative to work with. The potential field application of this technology would use a formulation containing the albino fungus-the bioactive ingredient- in its yeast like form. However, some Ophiostoma strains cultures present a marked filamentous morphology in liquid culture medium, affecting the efficiency in the production of the bioactive ingredient. The hypothesis of this work presumed the possibility to control the morphology of Ophiostoma cultures, through the modification of growth conditions in liquid medium. The effect of inoculum size, growth temperature and agitation rate on the morphology of PcF2A29 Ophiostoma piceae and FlF1A55 Ophiostoma floccosum albino strains in liquid culture medium, was studied. A 23 factorial design was employed. The results showed that the initial inoculum size had a statistically significant effect on yeast-like growth morphology in both strains, whereas the temperature only produced a significant effect in PcF2A29 O. piceae strain.

6-Pentyl-α-pyrone as an anti-sapstain compound produced by Trichoderma gamsii KUC1747 inhibits the germination of ophiostomatoid fungi

The capability of Trichoderma gamsii to biologically control sapstain fungi has been investigated. Six ophiostomatoids, including Ophiostoma floccosum, O. piceae, O. piliferum, O. ips, Grosmannia koreana, and G. piceaperda, were inhibited by the extracts of T. gamsii. Of the various cultivation periods, 7 days of T. gamsii cultivation produced antifungal compounds most efficiently. The crude extracts of T. gamsii inhibited O. ips, G. koreana, and G. piceaperda by over 99%. The crude extracts of T. gamsii were isolated, and the compounds were purified by thin layer chromatography (TLC), open column chromatography, ultra-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) and NMR spectroscopy. The active fractions were separated based on the degree of T. gamsii antifungal activity. The compound 6-pentyl-α-pyrone (6PAP) was evaluated as a biological control agent for sapstain fungi.

Ophiostomatoid fungi isolated from fallen shoots of Scots pine pruned by Tomicus species in Poland

Ophiostomatoid fungi are known to be associated with <em>Tomicus</em> spp. on <em>Pinus sylvestris</em>. However, very little is actually known about the fungi present in the pine shoots damaged by these insects. The aim of this study was to survey species of <em>Ophiostoma</em> s.lato associated with fallen shoots of Scots pine pruned by <em>Tomicus</em> spp. in Poland. The study was conducted in four pure Scots pine stands in southern and south-western part of the country. Fungi were identified based on morphology and DNA sequence comparison for two gene (the ITS rDNA region and ß–tubulin). In total, 64 isolates obtained, represent seven species of ophiostomatoid fungi, including their asexual states of the genera. Two of them, <em>Ophiostoma</em> sp. 1 and <em>Sporothrix</em> sp. 1 probably represent new taxa. All species were found at very low frequencies. Among them, <em>Ophiostoma minus, Ophiostoma</em> sp. 1 and <em>Sporothrix</em> sp. 1 were the most frequently isolated, with a frequency of 2.0%. Occasionally, isolated species included <em>Leptographium piriforme, Ophiostoma canum, Ophiostoma floccosum</em> and <em>Grosmannia cucullata</em>-like. Association of species of Ophiostoma s. lato with <em>Tomicus</em> spp. and the taxonomic status of two new species are discussed.

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.