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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

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Enset (Ensete ventricosum) is an important starch staple crop, cultivated primarily in south and southwestern Ethiopia. Enset is the main crop of a sustainable indigenous African system that ensures food security in a country that is food deficient. Related to the banana family, enset is similarly affected by plant-parasitic nematodes. Plant-parasitic nematodes impose a huge constraint on agriculture. The distribution, population density and incidence of plant-parasitic nematodes of enset was determined during August 2018. A total of 308 fields were sampled from major enset-growing zones of Ethiopia. Eleven plant-parasitic nematode taxa were identified, with Pratylenchus (lesion nematode) being the most prominent genus present with a prominence value of 1460. It was present in each sample, with a highest mean population density per growing zone of 16 050 (10 g root)−1, although densities as high as 25 000 were observed in fields at higher altitudes in Guraghe (2200-3000 m a.s.l.). This lesion nematode is found in abundance in the cooler mountainous regions. Visible damage on the roots and corms was manifested as dark purple lesions. Using a combination of morphometric and molecular data, all populations were identified as P. goodeyi and similar to populations from Kenya, Uganda and Spain (Tenerife). Differences in population densities amongst cultivars indicate possible resistance of enset to P. goodeyi.

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The present study described a combining thermotherapy with meristem culture for improved eradication of onion yellow dwarf virus (OYDV) and shallot latent virus (SLV) from co‐infected in vitro‐cultured shallot shoots. In vitro‐cultured shoots infected with OYDV and SLV were thermo‐treated at a constant temperature of 36°C for 0, 2 and 4 weeks, and then meristems (0.5 mm) containing 1–2 leaf primordia were excised and cultured for shoot regrowth. Meristem culture without thermotherapy produced much higher levels of survival (100%) and shoot regrowth (55%) than those (62% survival and 32% shoot regrowth) produced by the procedure combining 4 weeks of thermotherapy with meristem culture. However, much higher virus‐free frequencies (70% for OYSV, 80% for SLV and 50% for both viruses) were obtained in the latter than those (10% for OYSV, 15% for SLV and 10% for both viruses) obtained in the former. Histological and subcellular studies showed that thermotherapy imposed stress or damage to the cells of meristems, thus resulting in reduced meristem survival and shoot regrowth. Studies on virus location revealed considerable alternations of virus distribution patterns in the thermo‐treated meristems. The results of histological and subcellular studies and analysis of virus distribution pattern added valuable experimental data in the combining thermotherapy with meristem culture for virus eradication. These data provided explanations as to why combining thermotherapy with meristem culture improved the eradication of OYDV and SLV from the virus‐infected in vitro shallot shoots.

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Lys ringråte på potet, forårsaket av bakterien Clavibacter michiganensis subspecies sepedonicus (Cms), har gjort mye skade i norsk potetproduksjon siden første påvisning i landet i 1964. Den er også grunnen til at man ikke kan eksportere poteter fra Norge. Siden 1965 har Norge hatt sitt eget, nasjonale regelverk for bekjempelse av bakterien. Man har tidligere ( før 1980) flere ganger uten hell forsøkt å utrydde sykdommen fra flere deler av landet. Dette fordi mangelen på en påvisningsmetode med tilstrekkelig sensitivitet den gangen gjorde det vanskelig å skaffe de nødvendige mengder sykdomsfrie settepoteter til utskiftingen...

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Rotgall nematoder (Meloidogyne spp.) er globalt de mest skadelige nematodene, og forårsaker mer enn 10 % av avlingsreduksjonen på verdensbasis. M. arenaria, M. javanica, M. incognita og M. hapla er de viktigste artene. Totalt er det beskrevet mer enn 90 arter av otgallnematoder, og av disse er ca. 20 så langt blitt funnet i Europa. M. chitwoodi and M. fallax betraktes som en trussel for Europa og begge artene forårsaker alvorlige kvalitetsskader på potet og grønnsaker som gulrot. På det europeiske kontinentet er M. hapla mest utbredt, mens M.chitwoodi og M. fallax er påvist i begrensede områder....

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Diseases caused by viruses threaten the production industry and food safety of aquaculture which is a great animal protein source. Grass carp reovirus (GCRV) has caused tremendous loss, and the molecular function of viral proteins during infection needs further research, as for most aquatic viruses. In this study, interaction between GCRV major outer capsid protein VP4 and RIG-I, a critical viral RNA sensor, was screened out by GST pull-down, endogenous immunoprecipitation and subsequent LC-MS/MS, and then verified by co-IP and an advanced farred fluorescence complementation system. VP4 was proved to bind to the CARD and RD domains of RIG-I and promoted K48-linked ubiquitination of RIG-I to degrade RIG-I. VP4 reduced mRNA and promoter activities of key genes of RLR pathway and sequential IFN production. As a consequence, antiviral effectors were suppressed and GCRV replication increased, resulting in intensified cytopathic effect. Furthermore, results of transcriptome sequencing of VP4 stably expressed CIK (C. idella kidney) cells indicated that VP4 activated the MyD88-dependent TLR pathway. Knockdown of VP4 obtained opposite effects. These results collectively revealed that VP4 interacts with RIG-I to restrain interferon response and assist GCRV invasion. This study lays the foundation for anti-dsRNA virus molecular function research in teleost and provides a novel insight into the strategy of immune evasion for aquatic virus.

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Sweet potato (Ipomoea batatas (L.) Lam.) is an important root crop for poor farmers in developing countries. Since the late 1980s, viral diseases have increasingly become a threat to sweet potato production in Ethiopia. This review paper presents the role of sweet potato production for ensuring food security, the level of sweet potato virus research, including the types of viral species identified and their current level of incidences in Ethiopia. Sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV), Sweet potato virus 2 (SPV2), Sweet potato virus G (SPVG), and Cucumber mosaic virus (CMV) were reported in Ethiopia, where the first two are the most common and exist at high incidences. In addition, this paper discusses the virus vectors, virus transmission methods to new farms, factors exacerbating the rate of viral incidence and the methods used to reduce the incidences. Moreover, it highlights methods of sweet potato viruses’ detection and cleaning of infected materials in use and the challenges encountered towards the efficient utilization of the methods. Finally, we suggest major intervention techniques that will integrate all key players in managing the impact of the virus on sweet potato production to improve productivity and ensuring food security in Ethiopia. The findings obtained from this review could be an input for the current research on sweet potato improvement (both planting materials and routines) in Ethiopia.

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Recently developed CRISPR-mediated base editors, which enable the generation of numerous nucleotide changes in target genomic regions, have been widely adopted for gene correction and generation of crop germplasms containing important gain-of-function genetic variations. However, to engineer target genes with unknown functional SNPs remains challenging. To address this issue, we present here a base-editing-mediated gene evolution (BEMGE) method, employing both Cas9n-based cytosine and adenine base editors as well as a single-guide RNA (sgRNA) library tiling the full-length coding region, for developing novel rice germplasms with mutations in any endogenous gene. To this end, OsALS1 was artificially evolved in rice cells using BEMGE through both Agrobacterium-mediated and particle-bombardment-mediated transformation. Four different types of amino acid substitutions in the evolved OsALS1, derived from two sites that have never been targeted by natural or human selection during rice domestication, were identified, conferring varying levels of tolerance to the herbicide bispyribac-sodium. Furthermore, the P171F substitution identified in a strong OsALS1 allele was quickly introduced into the commercial rice cultivar Nangeng 46 through precise base editing with the corresponding base editor and sgRNA. Collectively, these data indicate great potential of BEMGE in creating important genetic variants of target genes for crop improvement.