Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2000
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A rapid and sensitive method was developed to discriminate between Seiridium cardinale and Seiridium cupressi, the fungi causing severe cankers on common cypress in the Mediterranean area. The method amplified sequence variants in the ITS2 region of ribosomal DNA using the polymerase chain reaction (PCR), followed by polyacrylamide gel electrophoresis, to reveal single-strand conformation polymorphism (SSCP) between the two species. The greatest separation pattern was obtained with a gel matrix containing 7-10% formamide and 3-5% glycerol under optimized running conditions, which were found to be 30-40 V at 4-5 degrees C for 4-8 h. Sequence homology among isolates within each of the two species caused no mobility shifts, with all isolates displaying the same migration pattern. A few base differences between S. cardinale and S. cupressi caused markedly different migration patterns, allowing differentiation of the two pathogens. Differences between these fungi at the genetic level are consistent with known data on morphological, physiological and pathogenic characteristics. SSCP analysis constitutes a rapid and easy-to-perform method by which to recognize and distinguish closely related organisms, and has considerable potential for use in diagnosis and taxonomy.
Authors
Isabella BørjaEditors
Bjørn ØklandAbstract
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Three clones of Norway spruce (Picea abies) were studied for their response to mass-inoculation with the blue-stain fungus Ceratocystis polonica. The effect of different pretreatments (fungal inoculation and wounding) before mass-inoculation was investigated for their possible role in an acquired resistance reaction.Pretreated trees showed enhanced resistance to the subsequent mass-inoculation relative to control trees that received no pretreatment. Furthermore, the fungal colonization of inoculated trees was less than that of wounded trees. The phenolic content of the bark, analysed by RP-HPLC, was compared in trees receiving different treatments.Trees inoculated with C. polonica had higher average concentration of ()-catechin, taxifolin and trans-resveratrol than wounded trees. Both inoculated and wounded trees had higher average concentrations of these compounds than control trees.The effect of the phenolic extract of Norway spruce bark on the growth of the root rot fungus Heterobasidion annosum and the blue-stain fungi C. polonica and Ophiostoma penicillatum were investigated in vitro. Heterobasidion annosum was not negatively affected, and the extracts had fungistatic effects on the blue-stain fungi. The growth of O. penicillatum was more inhibited than the growth of the more aggressive C. polonica.
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We have studied how callus cultures from two clones of Norway spruce influence the growth of two pathogens, Ceratocystis polonica and Heterobasidion annosum, when co-cultivated in vitro. In field experiments, trees of clone 409 were susceptible to both fungi, whereas clone 589 was less affected. Callus was cultured on medium containing cytokinins (benzylaminopurine, kinetin) and with or without auxin (2,4-dichlorphenoxy acetic acid). For co-cultivation with fungus, one piece of callus was placed towards the edge of each Petri dish. One and 14 days after inoculation with callus the dishes were co-inoculated with the fungus. Both clones strongly stimulated the initial growth of both fungi. Clone 589 inhibited the growth of both fungi when the fungi were inoculated one day after the callus. When the callus was cultured on medium without auxin for 14 days before co-inoculation clone 589 strongly inhibited the growth of both fungi, whereas clone 409 inhibited H. annosum only.
Authors
Dan AamlidAbstract
Two fungi, V. heterodoxa and P. vaccinii, are found to have impact on the leaf coverage of bilberry plants. When studying vegetation or forest ecosystems, assessors should, therefore, be aware of the biotic impact of pathogens on plants.