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.
2018
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Eveliina Kallioniemi Knut HovstadAbstract
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Different seed lots of Pinus spp. cultivated within South Africa were screened for the presence or absence of seed-borne fungi according to modified ISTA (International Seed Testing Association) prescribed protocols. Numerous (454 isolates) fungi were successfully isolated, purified and stored using agar slants and cryopreservation. Sydowia polyspora was isolated from six different seed lots from three Pinus species (P. greggii (South), P. elliottii and P. taeda) and was morphologically and molecularly identified. Koch’s postulates was fulfilled by inoculating one year old seedlings (wounded and unwounded) with a spore suspension (107 ml-1) obtained from 30 day old pure cultures grown on PDA. Inoculated and uninoculated control seedlings were incubated in a greenhouse at 220C until symptom development. Sydowia polyspora was re-isolated from symptomatic needles with both wounded and unwounded needles showing characteristic symptoms. No symptoms were apparent on the control seedlings. To the best of our knowledge, this is the first report of the fungus being isolated and recorded within the country. Further investigations will look at the prevalence, pathogenicity and characterization of the fungus within South Africa.
Authors
Michael Roleda Jorunn Skjermo Hélène Marfaing Rosa Jonsdottir Celine Rebours Anna Gietl Dagmar B. Stengel Udo NitschkeAbstract
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In this paper, we examine citizen and consumer attitudes towards, and preferences for, private and public goods from organic agriculture in Norway. The study is based on a survey among 939 Norwegians. The results show that in the role as citizens, the respondents hold a moderate belief in the superiority of organic farming concerning the production of public goods, but they give relatively low priority to prompting organic farming compared to other agricultural policy goals. In the role as consumers (choice experiment), the respondents were willing to pay for several attributes of organic food. Only 6% of the respondents buy organic food as often as they can. The most important reasons for buying organic food are health and environmental concerns, while animal welfare has little importance. Lack of perceived superiority regarding health benefits, taste, safety and environment are important reasons for not consuming (more) organic food among those who rarely or never buy organic food.
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Bark beetles and their symbiotic bluestain fungi kill more trees than all other natural factors and cause great economic losses in Norway spruce and other conifers. The tree's natural defenses are the most important factor maintaining bark beetle-fungus complexes at low, endemic levels. Spraying Norway spruce trees with the plant hormone methyl jasmonate (MeJA) primes tree defenses without eliciting notable induced defenses, but enables the trees to respond much more quickly and strongly when challenged by bark beetles or fungi several weeks after treatment. This phenomenon, known as defense priming, is a form of acquired resistance that enables cost-effective and vigorous defense responses. In field experiments with 50-year-old clonal spruce trees terpene concentrations in the bark increased 60-fold within 24 h after mechanical wounding of MeJA primed trees, compared with a 13-fold increase in unprimed control trees. We also observed altered transcriptional patterns in primed trees using Illumina deep transcriptome sequencing. When wounded, primed trees launched vigorous induced defenses with significant differential regulation of gene transcripts, such as those involved in phenylpropanoid synthesis leading to lignification. Resistance-like genes, such as the NB-LRR coding genes, are also more rapidly induced in primed than in unprimed trees. Transcriptome results from primed but unwounded trees indicate an alteration in the state of the chromatin, resembling changes associated with the activity of the epigenetic machinery creating long-lasting epigenetic marks. We do not know yet how long the primed state is activated in Norway spruce, but our data so far indicate that it may last for at least 3 years.
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