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Träfflista för sökning "WFRF:(Persson Anna) ;pers:(Kolseth Anna Karin)"

Sökning: WFRF:(Persson Anna) > Kolseth Anna Karin

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2.
  • Didon, Ulla, et al. (författare)
  • Cover Crop Residues-Effects on Germination and Early Growth of Annual Weeds
  • 2014
  • Ingår i: Weed Science. - 0043-1745 .- 1550-2759. ; 62, s. 294-302
  • Tidskriftsartikel (refereegranskat)abstract
    • There is an increasing interest in the use of cover crops in agriculture, in Sweden mainly for the use as catch crops to reduce nitrogen leakage. Some of these crops are known for their allelopathic abilities, which may play a role in the control of weeds and contribute to reduced herbicide use. This study aimed to explore the possible suppressive effect of the cover crop species white mustard, fodder radish, rye, and annual ryegrass on the early growth of the weed species silky windgrass, shepherd's-purse, and scentless false mayweed. In a greenhouse experiment using fresh cover crop residues, white mustard was the only crop that showed an effect. It reduced both seedling establishment, by 51 to 73%, and biomass, by 59 to 86%, of shepherd's-purse and scentless false mayweed. In contrast, in a growth chamber experiment using frozen material, mean germination time of silky windgrass was extended by 20 to 66% by all cover crops. Also, three out of four cover crops reduced root growth in scentless false mayweed by 40 to 46%, and two out of four cover crops reduced root growth in shepherd's-purse by 13 to 61%. However, considering seedling survival, white mustard was the most prominent cover crop, reducing survival by 21 to 57% in shepherd's-purse and scentless false mayweed. In this paper we provide evidence that different weed species show different response to different cover crops under climatic conditions prevailing in Scandinavia. Such results emphasize the importance of understanding weed cover crop interactions as necessary for developing cropping systems that can utilize cover crops to suppress local weed flora.
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3.
  • Karlsson, Ida, et al. (författare)
  • Agricultural factors affecting Fusarium communities in wheat kernels
  • 2017
  • Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 0168-1605 .- 1879-3460. ; 252, s. 53-60
  • Tidskriftsartikel (refereegranskat)abstract
    • Fusarium head blight (FHB) is a devastating disease of cereals caused by Fusarium fungi. The disease is of great economic importance especially owing to reduced grain quality due to contamination by a range of mycotoxins produced by Fusarium. Disease control and prediction is difficult because of the many Fusarium species associated with FHB. Different species may respond differently to control methods and can have both competitive and synergistic interactions. Therefore, it is important to understand how agricultural practices affect Fusarium at the community level.Lower levels of Fusariwn mycotoxin contamination of organically produced cereals compared with conventionally produced have been reported, but the causes of these differences are not well understood. The aim of our study was to investigate the effect of agricultural factors on Fusarium abundance and community composition in different cropping systems. Winter wheat kernels were collected from 18 organically and conventionally cultivated fields in Sweden, paired based on their geographical distance and the wheat cultivar grown. We characterised the Fusarium community in harvested wheat kernels using 454 sequencing of translation elongation factor 1-alpha amplicons. In addition, we quantified Fusariwn spp. using real-time PCR to reveal differences in biomass between fields.We identified 12 Fusariwn operational taxonomic units (OTUs) with a median of 4.5 OTUs per field. Fusarium graminearum was the most abundant species, while F. avenaceum had the highest occurrence. The abundance of Fusariwn spp. ranged two orders of magnitude between fields. Two pairs of Fusariurt species co-occurred between fields: F. poae with F. tricinctwn and F. culmorwn with F. sporofrichoides. We could not detect any difference in Fusariwn communities between the organic and conventional systems. However, agricultural intensity, measured as the number of pesticide applications and the amount of nitrogen fertiliser applied, had an impact on Fusariwn communities, specifically increasing the abundance of F. tricinctwn. There were geographical differences in the Fusarium community composition where F. graminearwn was more abundant in the western part of Sweden. The application of amplicon sequencing provided a comprehensive view of the Fusarium community in cereals. This gives us better opportunities to understand the ecology of Fusarium spp., which is important in order to limit FHB and mycotoxin contamination in cereals.
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4.
  • Karlsson, Ida, et al. (författare)
  • Genus-Specific Primers for Study of Fusarium Communities in Field Samples
  • 2016
  • Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 82, s. 491-501
  • Tidskriftsartikel (refereegranskat)abstract
    • Fusarium is a large and diverse genus of fungi of great agricultural and economic importance, containing many plant pathogens and mycotoxin producers. To date, high-throughput sequencing of Fusarium communities has been limited by the lack of genus-specific primers targeting regions with high discriminatory power at the species level. In the present study, we evaluated two Fusarium- specific primer pairs targeting translation elongation factor 1 (TEF1). We also present the new primer pair Fa+7/Ra+6. Mock Fusarium communities reflecting phylogenetic diversity were used to evaluate the accuracy of the primers in reflecting the relative abundance of the species. TEF1 amplicons were subjected to 454 high-throughput sequencing to characterize Fusarium communities. Field samples from soil and wheat kernels were included to test the method on more-complex material. For kernel samples, a single PCR was sufficient, while for soil samples, nested PCR was necessary. The newly developed primer pairs Fa+7/Ra+6 and Fa/Ra accurately reflected Fusarium species composition in mock DNA communities. In field samples, 47 Fusarium operational taxonomic units were identified, with the highest Fusarium diversity in soil. The Fusarium community in soil was dominated by members of the Fusarium incarnatum-Fusarium equiseti species complex, contradicting findings in previous studies. The method was successfully applied to analyze Fusarium communities in soil and plant material and can facilitate further studies of Fusarium ecology.
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5.
  • Karlsson, Ida, et al. (författare)
  • Organic farming increases richness of fungal taxa in the wheat phyllosphere
  • 2017
  • Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 26, s. 3424-3436
  • Tidskriftsartikel (refereegranskat)abstract
    • Organic farming is often advocated as an approach to mitigate biodiversity loss on agricultural land. The phyllosphere provides a habitat for diverse fungal communities that are important for plant health and productivity. However, it is still unknown how organic farming affects the diversity of phyllosphere fungi in major crops. We sampled wheat leaves from 22 organically and conventionally cultivated fields in Sweden, paired based on their geographical location and wheat cultivar. Fungal communities were described using amplicon sequencing and real-time PCR. Species richness was higher on wheat leaves from organically managed fields, with a mean of 54 operational taxonomic units (OTUs) compared with 40 OTUs for conventionally managed fields. The main components of the fungal community were similar throughout the 350-km-long sampling area, and seven OTUs were present in all fields: Zymoseptoria, Dioszegia fristingensis, Cladosporium, Dioszegia hungarica, Cryptococcus, Ascochyta and Dioszegia. Fungal abundance was highly variable between fields, 10(3)-10(5) internal transcribed spacer copies per ng wheat DNA, but did not differ between cropping systems. Further analyses showed that weed biomass was the strongest explanatory variable for fungal community composition and OTU richness. These findings help provide a more comprehensive understanding of the effect of organic farming on the diversity of organism groups in different habitats within the agroecosystem.
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6.
  • Kolseth, Anna-Karin, et al. (författare)
  • Dispersal paaterns of F. graminearum and possible implications for disease development in the field
  • 2012
  • Ingår i: NJF Report. - 1653-2015. ; 8, s. 33-
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Focusing on F. graminearum, results from two studies on inter species interactions of Fusarium will be discussed. The two studies have different inoculation strategies, one using inoculated sterilized kernels placed at sowing depth as inoculum, and the other using spray inoculation of dissolved conidia on the panicle, at flowering stage. Both studies were performed in growth chambers with oat as a host but they differed considering the choice of Fusarium species studied. The first study, with inoculum at sowing depth used F. graminearum, F. culmorum and F. langsethiae as models, while the spray inoculation study focused on F. graminearum, F. avenaceum and F. langsethiae. In both studies Fusarium inoculations were performed with both single species and different combinations of species mixtures. Infection development in both studies was quantified using real-time PCR. When placing inoculum at sowing depth, following the development of fungal infection over time, F. culmorum was detected earlier during plant development compared to F. graminearum in roots, stem bases and first nodes (DC 60). At a later stage (DC 90), F. graminearum had caught up, but the two species did show a different colonization pattern. While a large proportion of sampled plants had detectable F. culmorum DNA in roots, stem bases and first nodes (23 of 50 plants inoculated with F. culmorum), no infection of this species was found in the panicles. In comparison, F. graminearum was found in roots, stem bases and first nodes in only 3 of 38 plants inoculated with F. graminearum. It had on the other hand spread and contaminated pots with other inoculation treatments, and was found in almost all panicles in the growth chamber irrespective of inoculation treatment. Infection of F. langsethiae was not detectable using real-time PCR in any sampled material in any growth stage. Pots inoculated with F. langsethiae at sowing depth showed a lower cross contamination of F. graminearum in roots, stem bases and first nodes compared to the control pots, but no difference was found in F. graminearum panicle infections, comparing uninoculated control pots with F. langsethiae inoculated pots. Applying inoculum directly to the panicle using spray inoculation, following the development of the infection over 2 weeks (sampling 2, 6, 10 and 14 days after inoculation), reveals an effect of the two other species on F. graminearum. When F. graminearum was co-inoculated with either F. avenaceum or F. langsethiae or both, F. graminearum did show a lower infection rate at all time-points compared to when it was inoculated singly. Results imply that F. graminearum has a preference for air dispersal entering the plant in to the panicle. Results also imply that this species is poor at interference competition in planta. Recent outbreaks of F. graminearum in Scandinavia may be explained by an optimal seasonal climate, but can the dispersal pattern of F. graminearum also be of importance? By being good at dispersal it may be the first one to establish on the host, and thereby gain a competitive advantage over other Fusarium species.
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9.
  • Kolseth, Anna-Karin, et al. (författare)
  • Plant Pathogenic Fungal Interactions in Oats
  • 2011
  • Ingår i: NJF Report. - 1653-2015. ; 7, s. 194-194
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Within the genus Fusarium more than fifteen species have been identified associated with cereal plant material, and in most cases more than one species are simultaneously present in a sample. Some of the species are aggressive plant pathogens causing Fusarium Head Blight, FHB, while other species are minor pathogens causing very little or no symptoms. Jointly for the cereal Fusarium species is that they produce mycotoxins harmful for both humans and animals. This makes them both a quantitative and qualitative problem. To study inter Fusarium species biology and to test the hypothesis that the minor cereal pathogen Fusarium langsethiae is dependent on other Fusarium spp. for a successful infection of its host a growth chamber experiment was carried out. Two different levels of humidity but same temperature were used in order to study development and interactions between Fusarium culmorum, Fusarium graminearum and Fusarium langsethiae in oat. The different Fusarium species was used singly or in different pair-mixtures and the fungi were inoculated on sterile cereal kernels. The fungal inoculum was placed at sowing depth in the pots and sampling of plants was performed five times with regular intervals until the plants started its yellowing phase. Preliminary analysis of plants at yellowing phase reveals no detectable endophytic infection of F. langsethiae suggesting it has an epiphytic life style. Its pattern of infection also confirms it being a minor pathogen, since it did not cause early plant death, which, in comparison, both F. graminearum and F. culmorum did. Fusarium graminearum and F. culmorum showed preference for different dispersal strategies with the former being easily wind dispersed and the latter more stationary and soil borne. Analysis is ongoing and further results will be presented and discussed
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10.
  • Persson, Paula, et al. (författare)
  • Do cereal Fusarium species need each other? - Discussion on microbial interactions in the field
  • 2010
  • Ingår i: Bioforsk Fokus. - 0809-8662. ; 5, s. 26-
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • More than fifteen Fusarium spp. have been identified associated with cereal plant material. Experience has shown that in most cases more than one species are present in a sample simultaneously. Another observation is that specific Fusarium species appear together frequently. Implications and questions of the within Fusarium species interactions and the interactions with other pathogens and saprophytes will be discussed. At our department a two-year cropping system field experiment has been performed studying a co-inoculation with the cereal pathogens Fusarium culmorum and Bipolaris sorokinia. The pathogens were introduced as fungal inoculum on barley kernels (autoclaved kernels inoculated with pure culture, incubated three weeks) at the sowing time for five different preceding crops (barley, wheat, wheat undersown with red clover, oat and pea) grown before a malting barley crop. The trial was repeated once and the results showed that both pathogens were able to grow side by side in the preceding crop and were both successfully transferred to the following barley crop. In cool and wet growing conditions equal number of barley plants showed to be infected with the two pathogens, independent of preceding crop. In a dryer and warmer season F. culmorum was the weaker pathogen and a significantly lower amount of plants were infected compared to B. sorokiniana. In the dryer climate the infection rate for B. sorokiniana in the malting barley was significantly higher grown after the preceding crops barley and wheat, compared with the other preceding crops. To study inter Fusarium species biology and to test the hypothesis that the minor cereal pathogen Fusarium langsethiae are dependent on other Fusarium spp for a successful infection a growth chamber experiment was carried out. Different levels of humidity were used in order to study development and interactions between Fusarium culmorum, Fusarium graminearum and Fusarium langsethiae on oat. Environmental conditions were based on weather from years with high levels of DON and HT-2/T-2 and on scenarios for future climate change, resulting in two different climatic treatments; warm/dry (max temp 22°C/min 55% RH) and warm/humid (max temp 22°C/min 70% RH). Inoculum of the different Fusarium species was used in monoculture or in different polycultures, but no more than two species were mixed. Inoculum was placed at sowing depth in the pots and sampling was performed at regular intervals, every two weeks after emergence of the oat plants, throughout the growth. Analysis of samples from roots, stem base, first node and kernels using quantitative real-time PCR is ongoing and the first results from this experiment will be presented and discussed.
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