Sammendrag

Bakterien Erwinia amylovora kan gjøre stor skade på eple, pære og prydbusker i rosefamilien. Bakterien infiserer primært fruktblomstene, men kan også angripe nye blader og skudd. Sykdommen har hittil ikke blitt påvist i Norge i kjernefrukt (bortsett fra noen få tilfeller i privathager), kun i andre vertplanter som for eksempel mispelarter. Frem til november 2015 har import av vertplanter for pærebrann til Norge vært forbudt, men myndighetene har nå åpnet for import fra land hvor pærebrann er kjent å forekomme. Det var derfor ønskelig å få kunnskap om smittestatus i sendingene som i 2016 ble mottatt fra Nederland og Belgia. Disse sendingene bestod av om lag 150000 trær og grunnstammer av eple, Malus domestica. Det ble sendt inn og analysert 510 prøver (0,34%) fra Mattilsynets kontorer region Stor-Oslo, Region Øst og Region Sør og Vest. Alle prøver ble undersøkt med internasjonalt anbefalte og anerkjente analysemetoder. Erwinia amylovora ble ikke påvist i noen av prøvene.

Sammendrag

The prevalence of Fusarium dry rot in potatoes produced in Norway was investigated in a survey for three consecutive years in the period 2010 to 2012. A total of 238 samples (comprising 23,800 tubers) were collected, representing different cultivars and production regions in Norway. Fusarium spp. were detected in 47% of the samples, with one to three species per sample. In total, 718 isolates of Fusarium spp. were recovered and identified to seven species. The most commonly isolated species was Fusarium coeruleum, comprising 59.6% of the total Fusarium isolates and found in 17.2% of the collected samples, followed by Fusarium avenaceum (27.2% of the isolates and found in 27.7% of the samples). Fusarium sambucinum was the third most prevalent species (6.4% in 8.8% of the samples) and Fusarium culmorum the fourth (5.2% in 6.3% of the samples). Less prevalent species included Fusarium cerealis, Fusarium graminearum, and Fusarium equiseti (<1% in 0.4 to 1.3% of the samples). F. coeruleum was the most prevalent species in northern and southwestern Norway, whereas F. avenaceum was dominating in eastern Norway. The potato cultivars Berber and Rutt were susceptible to all Fusarium spp. A new TaqMan real-time PCR assay specific for F. coeruleum was developed, which successfully identified Norwegian isolates. This and other previously developed real-time PCR assays targeting different Fusarium species were evaluated for their ability to detect latent infections in potatoes at harvest. This study provides new information on the current occurrence of different Fusarium species causing Fusarium dry rot in potatoes in Europe including areas far into the arctic in the north of Norway.

Sammendrag

Phytophthora cactorum causes crown rot in strawberry (Fragaria x ananassa Dutch.), which is characterized by wilting and eventually collapse of the plant. An efficient control measure is the use of resistant cultivars, however most commercial cultivars are susceptible to the disease. The aim of our work is to generate basic knowledge about P. cactorum resistance as well as to develop genetic markers that can be used as tools for development of resistant cultivars. The genetic complexity of the octoploid cultivated strawberry, has led to development of the diploid wild strawberry (F. vesca) as a model system for Fragaria. We have identified suitable parents after screening accessions of diploid Fragaria sp. for resistance [1], and generated a mapping population which we are currently characterizing. In order to study the plant-pathogen interaction in detail we have identified and characterized resistance genes from diploid strawberry and effector genes from P. cactorum using different transcriptional analysis techniques; nucleotide-binding site (NBS)-profiling for resistance genes, and suppression subtractive hybridization (SSH) as well as a designed effector-specific differential display (ESDD) for genes involved in pathogenicity.   This work is supported by The Research Council of Norway.   [1] Eikemo H, Brurberg MB, Davik J (2010). Resistance to Phytophthora cactorum in diploid Fragaria species. HortScience. 45:193-197.