Heksekost på eple – nye utbrudd

Heksekost på eple er en karanteneskadegjører. Høsten 2010 er det påvist heksekost i eple fra 11 frukthager, 10 i Sogn og 1 i Telemark. Sannsynligvis står det infiserte trær på mange flere steder. I Sogn er det funnet heksekost både i Leikanger/Hermansverk, Slinde, Ylvisåker og Lærdal. I frukthagene med påvist smitte var det tydelig redusert fruktstørrelse på flere sorter, særlig var dette framtredende i sorten Discovery.publishedVersio

Genome analysis of Phytophthora cactorum strains associated with crown- and leather-rot in strawberry

Phytophthora cactorum has two distinct pathotypes that cause crown rot and leather rot in strawberry (Fragaria × ananassa). Strains of the crown rot pathotype can infect both the rhizome (crown) and fruit tissues, while strains of the leather rot pathotype can only infect the fruits of strawberry. The genome of a highly virulent crown rot strain, a low virulent crown rot strain, and three leather rot strains were sequenced using PacBio high fidelity (HiFi) long read sequencing. The reads were de novo assembled to 66.4–67.6 megabases genomes in 178–204 contigs, with N50 values ranging from 892 to 1,036 kilobases. The total number of predicted complete genes in the five P. cactorum genomes ranged from 17,286 to 17,398. Orthology analysis identified a core secretome of 8,238 genes. Comparative genomic analysis revealed differences in the composition of potential virulence effectors, such as putative RxLR and Crinklers, between the crown rot and the leather rot pathotypes. Insertions, deletions, and amino acid substitutions were detected in genes encoding putative elicitors such as beta elicitin and cellulose-binding domain proteins from the leather rot strains compared to the highly virulent crown rot strain, suggesting a potential mechanism for the crown rot strain to escape host recognition during compatible interaction with strawberry. The results presented here highlight several effectors that may facilitate the tissue-specific colonization of P. cactorum in strawberry.publishedVersio

Transcriptional profiling of defense responses to Botrytis cinerea infection in leaves of Fragaria vesca plants soil-drenched with beta-aminobutyric acid

Grey mold caused by the necrotrophic fungal pathogen Botrytis cinerea can affect leaves, flowers, and berries of strawberry, causing severe pre- and postharvest damage. The defense elicitor beta-aminobutyric acid (BABA) is reported to induce resistance against B. cinerea and many other pathogens in several crop plants. Surprisingly, BABA soil drench of woodland strawberry (Fragaria vesca) plants two days before B. cinerea inoculation caused increased infection in leaf tissues, suggesting that BABA induce systemic susceptibility in F. vesca. To understand the molecular mechanisms involved in B. cinerea susceptibility in leaves of F. vesca plants soil drenched with BABA, we used RNA sequencing to characterize the transcriptional reprogramming 24 h post-inoculation. The number of differentially expressed genes (DEGs) in infected vs. uninfected leaf tissue in BABA-treated plants was 5205 (2237 upregulated and 2968 downregulated). Upregulated genes were involved in pathogen recognition, defense response signaling, and biosynthesis of secondary metabolites (terpenoid and phenylpropanoid pathways), while downregulated genes were involved in photosynthesis and response to auxin. In control plants not treated with BABA, we found a total of 5300 DEGs (2461 upregulated and 2839 downregulated) after infection. Most of these corresponded to those in infected leaves of BABA-treated plants but a small subset of DEGs, including genes involved in 'response to biologic stimulus', 'photosynthesis' and 'chlorophyll biosynthesis and metabolism', differed significantly between treatments and could play a role in the induced susceptibility of BABA-treated plants.Peer reviewe

Sluttrapport i prosjektet Grøntanleggshygiene 2011

Internasjonal handel med plantemateriale spreier ulike skadeorganismar, noko som har store, negative konsekvensar for plantehelsa verda over. Spesielt hytophthora-artar har stort skadepotensiale og hadde difor hovudfokus i dette prosjektet. I fleire norske grøntanlegg har det vorte funne omfattande angrep av P. ramorum på rododendron , ein skadegjerar som har ført til epidemi ar på skog både i USA og England. I England er no om lag 3 million ar japanlerk (Larix kaempferi) felt på grunn av P. ramorum. I prosjektet Grøntanleggshygiene i 2011 fann vi P. ramorum i ei elv som renn gjennom Bryne sentrum og i ein bekk ved Gamlehaugen i Bergen. Vatn kan føra smitten med seg, så denne organismen er truleg spreidd langt utover grøntanlegg. Med eit klima langs vestlandskysten som liknar det ein har på vestkysten av England, kan vi ikkje utelukka at vi kan koma til å få epidemiske utbrot i skog-og naturområde også her i landet. I prosjektet fann vi også fleire andre Phytophthora-artar i vatn. I bøkeskogen i Larvik påviste vi angrep av P. cambivora, ein art som gjer stor skade på bøk mellom anna i Sverige. Vidare kartlegging og overvaking må difor ha høg prioritet framover.publishedVersio

Pervasive fungicide resistance in Botrytis from strawberry in Norway: Identification of the grey mould pathogen and mutations

Control of grey mould, caused by Botrytis spp., is a major challenge in open field strawberry production. Botrytis was isolated from plant parts collected from 19 perennial strawberry fields with suspected fungicide resistance in the Agder region of Norway in 2016. Resistance to boscalid, pyraclostrobin and fenhexamid was high and found in 89.1%, 86.0% and 65.4% of conidia samples, respectively. Multiple fungicide resistance was common; 69.6% of conidia samples exhibited resistance to three or more fungicides. Botrytis group S and B. cinerea sensu stricto isolates were obtained from 19 and 16 fields, respectively. The sdhB, cytb, erg27 and mrr1 genes of a selection of isolates were examined for the presence of mutations known to confer fungicide resistance to boscalid, pyraclostrobin, fenhexamid and pyrimethanil plus fludioxonil, respectively. Allele-specific PCR assays were developed for efficient detection of resistance-conferring mutations in cytb. Among B. cinerea isolates, 84.7%, 86.3% and 61.3% had resistance-conferring mutations in sdhB, cytb and erg27, respectively. A triplet deletion in mrr1, resulting in ΔL497, commonly associated with the multidrug resistance phenotype MDR1h, was detected in 29.2% of Botrytis group S isolates. High frequencies of resistance to several fungicides were also detected in Botrytis from both imported and domestically produced strawberry transplants. Fungicide resistance frequencies were not different among fields grouped by level of grey mould problem assessed by growers, indicating factors other than fungicide resistance contributed to control failure, a fact that has important implications for future management of grey mould.publishedVersio

Rapport for OK-program Xanthomonas arboricola pv pruni. Sesong 2016

Bakterien Xanthomonas arboricola pv. pruni kan gi stor skade i planter av Prunus slekten, især plomme. Bakterien har ikke vært påvist i Norge før man begynte med systematisk kartlegging. Målsettingen for programmet i 2016 var å få mer kunnskap om utbredelse i Norge. Først og fremst skulle nyplantinger av plomme, søt- og sur-kirsebær i kommersielle frukthager undersøkes. Mattilsynet har organisert prøveuttaket. Det ble i 2016 totalt sendt inn 356 prøver for analyse, ingen av dem viste seg å inneholde smitte av bakterien Xanthomonas arboricola pv. pruni.The bacterium Xanthomonas arboricola pv. pruni can cause great damage to plants of the Prunus genus, especially plum. The bacterium had not been detected in Norway before systematic surveys were started, the goal of the survey was to document the status of this bacterium in the country. The Norwegian Food Safety Authority has organized the selection of samples from domestic plant production of Prunus sp. In 2016 a total of 356 samples were submitted for analysis, none of them was found to be infected by the bacterium Xanthomonas arboricola pv. pruni.publishedVersio

Genome-wide analysis of signal peptide functionality in Lactobacillus plantarum WCFS1

<p>Abstract</p> <p>Background</p> <p><it>Lactobacillus plantarum </it>is a normal, potentially probiotic, inhabitant of the human gastrointestinal (GI) tract. The bacterium has great potential as food-grade cell factory and for <it>in situ </it>delivery of biomolecules. Since protein secretion is important both for probiotic activity and in biotechnological applications, we have carried out a genome-wide experimental study of signal peptide (SP) functionality.</p> <p>Results</p> <p>We have constructed a library of 76 Sec-type signal peptides from <it>L. plantarum </it>WCFS1 that were predicted to be cleaved by signal peptidase I. SP functionality was studied using staphylococcal nuclease (NucA) as a reporter protein. 82% of the SPs gave significant extracellular NucA activity. Levels of secreted NucA varied by a dramatic 1800-fold and this variation was shown not to be the result of different mRNA levels. For the best-performing SPs all produced NucA was detected in the culture supernatant, but the secretion efficiency decreased for the less well performing SPs. Sequence analyses of the SPs and their cognate proteins revealed four properties that correlated positively with SP performance for NucA: high hydrophobicity, the presence of a transmembrane helix predicted by TMHMM, the absence of an anchoring motif in the cognate protein, and the length of the H+C domain. Analysis of a subset of SPs with a lactobacillal amylase (AmyA) showed large variation in production levels and secretion efficiencies. Importantly, there was no correlation between SP performance with NucA and the performance with AmyA.</p> <p>Conclusion</p> <p>This is the first comprehensive experimental study showing that predicted SPs in the <it>L. plantarum </it>genome actually are capable of driving protein secretion. The results reveal considerable variation between the SPs that is at least in part dependent on the protein that is secreted. Several SPs stand out as promising candidates for efficient secretion of heterologous proteins in <it>L. plantarum</it>. The results for NucA provide some hints as to the sequence-based prediction of SP functionality, but the general conclusion is that such prediction is difficult. The vector library generated in this study is based on exchangeable cassettes and provides a powerful tool for rapid experimental screening of SPs.</p

Rapport for OK-program Xanthomonas arboricola pv pruni. Sesong 2015

Bakterien Xanthomonas arboricola pv. pruni kan gi stor skade i planter av Prunus slekten, især plomme. Bakterien har ikke vært påvist i Norge før denne kartleggingen ble gjennomført. Målsettingen var å dokumentere status for denne skadegjøreren i plantemateriale av plomme, både i import og i norsk produksjon. Mattilsynet har organisert prøveuttaket. Det ble fra og med desember 2014 og ut 2015 totalt sendt inn 799 prøver for analyse, 49 av dem viste seg å inneholde smitte av bakterien Xanthomonas arboricola pv. pruni. Bakterien ble påvist i 38 importprøver av plomme (grunnstammer fra Nederland) og 11 prøver fra norske planteprodusenter (nasjonal kartlegging). Dette tilsvarer en infeksjonsgrad av 15% i importprøvene og av 2% i prøver fra nasjonal kartlegging. Kun ett funn ble gjort i Prunus lauroceracus, 48 derimot i Prunus domestica

Rapport for OK-program Xanthomonas arboricola pv pruni. Sesong 2016

Bakterien Xanthomonas arboricola pv. pruni kan gi stor skade i planter av Prunus slekten, især plomme. Bakterien har ikke vært påvist i Norge før man begynte med systematisk kartlegging. Målsettingen for programmet i 2016 var å få mer kunnskap om utbredelse i Norge. Først og fremst skulle nyplantinger av plomme, søt- og sur-kirsebær i kommersielle frukthager undersøkes. Mattilsynet har organisert prøveuttaket. Det ble i 2016 totalt sendt inn 356 prøver for analyse, ingen av dem viste seg å inneholde smitte av bakterien Xanthomonas arboricola pv. pruni.The bacterium Xanthomonas arboricola pv. pruni can cause great damage to plants of the Prunus genus, especially plum. The bacterium had not been detected in Norway before systematic surveys were started, the goal of the survey was to document the status of this bacterium in the country. The Norwegian Food Safety Authority has organized the selection of samples from domestic plant production of Prunus sp. In 2016 a total of 356 samples were submitted for analysis, none of them was found to be infected by the bacterium Xanthomonas arboricola pv. pruni.publishedVersio

Evaluation of Ethiopian maize cultivars for resistance to Fusarium verticillioides and fumonisin accumulation

The objective of this study was to find sources of resistance to Fusarium ear rot and fumonisin accumulation in maize germplasm. Totally 15 maize cultivars were evaluated by means of silk channel inoculation using a fumonisin producing F. verticillioides isolate in field trials during 2013 and 2014 cropping seasons. Fusarium ear rot severity was determined at harvest, and fumonisin content was quantified using competitive Enzyme Linked Immunosorbent Assay (ELISA). The percentage of infected kernels per maize ear after inoculation, ranged from 5% to 60% in 2013 and from 3% to 40% in 2014. Fumonisin accumulation in maize cultivars ranged from 2700 to 76300 µg/kg in 2013 and from 1800 to 52700 µg/kg in 2014. Maize cultivars Berihu, Melkassa-2, Melkassa-7, Melkassa-4, BHQP542 and MHQ-138 showed low level of ear rot (3.9% to 22.9%) and total fumonisins (2300 to 17300 µg/kg) across the two years experiment. Cultivars that had low disease severity are useful in breeding programs aiming at developing cultivars resistance to fumonisin accumulation