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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.

2021

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Sammendrag

Identifying and characterizing cold responsive genes in Fragaria vesca associated with or responsible for low temperature tolerance is a vital part of strawberry cultivar development. In this study we have investigated the transcript levels of eight genes, two dehydrin genes, three putative ABA-regulated genes, two cold–inducible CBF genes and the alcohol dehydrogenase gene, extracted from leaf and crown tissues of three F. vesca genotypes that vary in cold tolerance. Transcript levels of the CBF/DREB1 transcription factor FvCBF1E exhibited stronger cold up-regulation in comparison to FvCBF1B.1 in all genotypes. Transcripts of FvADH were highly up-regulated in both crown and leaf tissues from all three genotypes. In the ‘ALTA’ genotype, FvADH transcripts were significantly higher in leaf than crown tissues and more than 10 to 20-fold greater than in the less cold-tolerant ‘NCGR1363’ and ‘FDP817’ genotypes. FvGEM, containing the conserved ABRE promoter element, transcript was found to be cold-regulated in crowns. Direct comparison of the kinetics of transcript and protein accumulation of dehydrins was scrutinized. In all genotypes and organs, the changes of XERO2 transcript levels generally preceded protein changes, while levels of COR47 protein accumulation preceded the increases in COR47 RNA in ‘ALTA’ crowns.

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Climate change may result in increased root system stresses in strawberry cultivation, requiring cultivars with root and crown-related resistance and resiliency traits. Approaches to widen the genetic basis and improve tools for the incorporation of novel variation are relevant to plant breeding for changing climate. The pre-breeding project NORDFRUIT is a Nordic public-private-partnership project that aims to introduce novel genetic variation from new sources, support the use of existing genetic resources adapted to Nordic and Baltic cultivation conditions, and develop efficient tools to speed up germplasm evaluation in breeding programs for climate adaptation. Pre-evaluated genotypes of Fragaria chiloensis or Fragaria virginiana were used as parents in interspecific (species hybridization) crosses, re-creating the garden strawberry hybrid species, F. ×ananassa. The created F1 hybrid seedlings were propagated by runners for replicated phenotyping trials. A greenhouse assay to test root-shoot biomass partition, growth vigour and Phytophthora cactorum resistance in these small plants was scaled up from an earlier assay based on nutrient film technology (NFT). The observed variation in disease symptom appearance, root-shoot ratio, and root proliferation indicated promising traits in the strawberry hybrid material, to be exploited further in genomic studies and to develop genome-assisted resistance breeding. The on-going work also includes field testing of the same hybrid material to evaluate winter hardiness, powdery mildew incidence, and fruit traits.

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Sammendrag

Extreme cold and frost cause significant stress to plants which can potentially be lethal. Low temperature freezing stress can cause significant and irreversible damage to plant cells and can induce physiological and metabolic changes that impact on growth and development. Low temperatures cause physiological responses including winter dormancy and autumn cold hardening in strawberry (Fragaria) species, and some diploid F. vesca accessions have been shown to have adapted to low-temperature stresses. To study the genetics of freezing tolerance, a F. vesca mapping population of 143 seedlings segregating for differential responses to freezing stress was raised. The progeny was mapped using ‘Genotyping-by-Sequencing’ and a linkage map of 2,918 markers at 851 loci was resolved. The mapping population was phenotyped for freezing tolerance response under controlled and replicated laboratory conditions and subsequent quantitative trait loci analysis using interval mapping revealed a single significant quantitative trait locus on Fvb2 in the physical interval 10.6 Mb and 15.73 Mb on the F. vesca v4.0 genome sequence. This physical interval contained 896 predicted genes, several of which had putative roles associated with tolerance to abiotic stresses including freezing. Differential expression analysis of the 896 QTL-associated gene predictions in the leaves and crowns from ‘Alta’ and ‘NCGR1363’ parental genotypes revealed genotype-specific changes in transcript accumulation in response to low temperature treatment as well as expression differences between genotypes prior to treatment for many of the genes. The putative roles, and significant interparental differential expression levels of several of the genes reported here identified them as good candidates for the control of the effects of freezing tolerance at the QTL identified in this investigation and the possible role of these candidate genes in response to freezing stress is discussed.