Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2020
Forfattere
Anette SundbyeSammendrag
Det er ikke registrert sammendrag
Forfattere
Anette SundbyeSammendrag
Det er ikke registrert sammendrag
Forfattere
Anette SundbyeSammendrag
Det er ikke registrert sammendrag
Forfattere
Harrison Mburu Laura Cortada Solveig Haukeland Wilson Ronno Moses Nyongesa Zachary Kinyua Joel L. Bargul Danny CoyneSammendrag
Potato cyst nematodes (PCN), such as Globodera rostochiensis and Globodera pallida, are quarantine restricted pests of potato causing major yield and financial losses to farmers. G. rostochiensis was first reported from Kenya’s key potato growing area in 2015. We sought to determine the diversity, prevalence and distribution of PCN species across the country by conducting a country-wide survey between 2016 and 2018, which included a more focused, follow-up assessment in three key potato growing counties. A total of 1,348 soil samples were collected from 20 potato growing counties. Information regarding local potato farming practices, potato cultivar use, their diversity and availability was also recorded. PCN cysts were obtained from 968 samples (71.8%) in all the counties surveyed, with Nyandarua County recording the highest PCN field-incidence at 47.6%. The majority of PCN populations, 99.9%, were identified as G. rostochiensis, while G. pallida was recovered from just one field, in a mixed population with G. rostochiensis. Inconsistencies in PCR amplification efficiency was observed for G. rostochiensis using the recommended EPPO primers, compared with ITS primers AB28/TW81, indicating that this protocol cannot be entirely relied upon to effectively detect PCN. Egg density in Nyandarua County varied between 30.6 and 158.5 viable eggs/g soil, with an average egg viability of 78.9 ± 2.8% (min = 11.6%, max = 99.9%). The PCN-susceptible potato cultivar named Shangi was the most preferred and used by 65% of farmers due to its shorter dormancy and cooking time, while imported cultivars (Destiny, Jelly, Manitou, and Markies) with resistance to G. rostochiensis were used by 7.5% of farmers due to unavailability and/or limited access to seeds. Thus, most farmers preferred using their own farm-saved seeds as opposed to purchasing certified seeds. Establishing the distribution and prevalence of PCN and elucidating the local farming practices that could promote the spread of PCN is a necessary precursor to the implementation of any containment or management strategy in the country and ultimately across the region.
Forfattere
Torstein KvammeSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
L. Willocquet W.R. Meza B. Dumont B. Klocke T. Feike K.C. Kersebaum P. Meriggi V. Rossi Andrea Ficke A. Djurle S. SavarySammendrag
Wheat disease management in Europe is mainly based on the use of fungicides and the cultivation of resistant cultivars. Improving disease management implies the formal comparison of disease management methods in terms of both crop health and yield levels (attainable yield, actual yield), thus enabling an assessment of yield losses and yield gains. Such an assessment is not available for wheat in Europe. The objective of the analysis reported here is to provide an overview of wheat health and yield performance in field experiments in Europe. Data from field experiments in six European countries (Belgium, France, Germany, Italy, Norway, and Sweden) conducted between 2013 and 2017 were analysed to that aim. Relationships between multiple disease levels, yield, level of cultivar resistance, level of fungicide protection, and weather patterns were assessed. The analyses included 73 field experiments, corresponding to a total of 447 [fungicide protection level x cultivar] combinations. Analyses across the six countries led to ranking the importance of foliar wheat diseases as follows, in decreasing order: leaf blotch (septoria tritici blotch, septoria nodorum blotch, and tan spot), leaf rust, yellow rust, and powdery mildew. Fusarium head blight was observed in France and Italy, and stem rust was sporadically observed in Italy. Disease patterns, crop inputs (fertiliser, fungicides), and yields widely varied within and across countries. Disease levels were affected by the level of fungicide use, by cultivar resistance, as well as by weather patterns. While this analysis enables a better documentation of the status of wheat health in Europe, it also highlights the critical need for policies in Europe enabling a more judicious use of pesticides. First, common standards for field experiments are needed (experimental designs and protocols; disease assessment procedures and scales; references, including reference-susceptible cultivars); second, assessments in farmers’ fields – and not in research stations – are necessary; and third, there is a need to use available process-based crop models to estimate attainable yields, and so, yield losses.
Sammendrag
Key message A locus on wheat chromosome 2A was found to control feld resistance to both leaf and glume blotch caused by the necrotrophic fungal pathogen Parastagonospora nodorum. Abstract The necrotrophic fungal pathogen Parastagonospora nodorum is the causal agent of Septoria nodorum leaf blotch and glume blotch, which are common wheat (Triticum aestivum L.) diseases in humid and temperate areas. Susceptibility to Septoria nodorum leaf blotch can partly be explained by sensitivity to corresponding P. nodorum necrotrophic efectors (NEs). Susceptibility to glume blotch is also quantitative; however, the underlying genetics have not been studied in detail. Here, we genetically map resistance/susceptibility loci to leaf and glume blotch using an eight-founder wheat multiparent advanced generation intercross population. The population was assessed in six feld trials across two sites and 4 years. Seedling infltration and inoculation assays using three P. nodorum isolates were also carried out, in order to compare quantitative trait loci (QTL) identifed under controlled conditions with those identifed in the feld. Three signifcant feld resistance QTL were identifed on chromosomes 2A and 6A, while four signifcant seedling resistance QTL were detected on chromosomes 2D, 5B and 7D. Among these, QSnb.niab-2A.3 for feld resistance to both leaf blotch and glume blotch was detected in Norway and the UK. Colocation with a QTL for seedling reactions against culture fltrate from a Norwegian P. nodorum isolate indicated the QTL could be caused by a novel NE sensitivity. The consistency of this QTL for leaf blotch at the seedling and adult plant stages and culture fltrate infltration was confrmed by haplotype analysis. However, opposite efects for the leaf blotch and glume blotch reactions suggest that diferent genetic mechanisms may be involved.
Sammendrag
The necrotrophic fungal pathogen Parastagonospora nodorum causes Septoria nodorum blotch (SNB), which is one of the dominating leaf blotch diseases of wheat in Norway. A total of 165 P. nodorum isolates were collected from three wheat growing regions in Norway from 2015 to 2017. These isolates, as well as nine isolates from other countries, were analyzed for genetic variation using 20 simple sequence repeat (SSR) markers. Genetic analysis of the isolate collection indicated that the P. nodorum pathogen population infecting Norwegian spring and winter wheat underwent regular sexual reproduction and exhibited a high level of genetic diversity, with no genetic subdivisions between sampled locations, years or host cultivars. A high frequency of the presence of necrotrophic effector (NE) gene SnToxA was found in Norwegian P. nodorum isolates compared to other parts of Europe, and we hypothesize that the SnToxA gene is the major virulence factor among the three known P. nodorum NE genes (SnToxA, SnTox1, and SnTox3) in the Norwegian pathogen population. While the importance of SNB has declined in much of Europe, Norway has remained as a P. nodorum hotspot, likely due at least in part to local adaptation of the pathogen population to ToxA sensitive Norwegian spring wheat cultivars.
Forfattere
Min Lin Melanie Stadlmeier Volker Mohler Kar-Chun Tan Andrea Ficke James Cockram Morten LillemoSammendrag
Key message We identifed allelic variation at two major loci, QSnb.nmbu-2A.1 and QSnb.nmbu-5A.1, showing consistent and additive efects on SNB feld resistance. Validation of QSnb.nmbu-2A.1 across genetic backgrounds further highlights its usefulness for marker-assisted selection. Abstract Septoria nodorum blotch (SNB) is a disease of wheat (Triticum aestivum and T. durum) caused by the necrotrophic fungal pathogen Parastagonospora nodorum. SNB resistance is a typical quantitative trait, controlled by multiple quantitative trait loci (QTL) of minor efect. To achieve increased plant resistance, selection for resistance alleles and/or selection against susceptibility alleles must be undertaken. Here, we performed genetic analysis of SNB resistance using an eight-founder German Multiparent Advanced Generation Inter-Cross (MAGIC) population, termed BMWpop. Field trials and greenhouse testing were conducted over three seasons in Norway, with genetic analysis identifying ten SNB resistance QTL. Of these, two QTL were identifed over two seasons: QSnb.nmbu-2A.1 on chromosome 2A and QSnb.nmbu-5A.1 on chromosome 5A. The chromosome 2A BMWpop QTL co-located with a robust SNB resistance QTL recently identifed in an independent eightfounder MAGIC population constructed using varieties released in the United Kingdom (UK). The validation of this SNB resistance QTL in two independent multi-founder mapping populations, regardless of the diferences in genetic background and agricultural environment, highlights the value of this locus in SNB resistance breeding. The second robust QTL identifed in the BMWpop, QSnb.nmbu-5A.1, was not identifed in the UK MAGIC population. Combining resistance alleles at both loci resulted in additive efects on SNB resistance. Therefore, using marker assisted selection to combine resistance alleles is a promising strategy for improving SNB resistance in wheat breeding. Indeed, the multi-locus haplotypes determined in this study provide markers for efcient tracking of these benefcial alleles in future wheat genetics and breeding activities.