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Strawberry powdery mildew (Podosphaera aphanis Wallr.) is a pathogen which infects the leaves, fruit, stolon and flowers of the cultivated strawberry (Fragaria ×ananassa), causing major yield losses, primarily through unmarketable fruit. The primary commercial control of the disease is the application of fungicidal sprays. However, as the use of key active ingredients of commercial fungicides is becoming increasingly restricted, interest in developing novel strawberry cultivars exhibiting resistance to the pathogen is growing rapidly. In this study, a mapping population derived from a cross between two commercial strawberry cultivars (‘Sonata’ and ‘Babette’) was genotyped with single nucleotide polymorphism (SNP) markers from the Axiom iStraw90k genotyping array and phenotyped for powdery mildew susceptibility in both glasshouse and field environments. Three distinct, significant QTLs for powdery mildew resistance were identified across the two experiments. Through comparison with previous studies and scrutiny of the F. vesca genome sequence, candidate genes underlying the genetic control of this trait were identified.

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To assess underlying metabolic processes and regulatory mechanisms during cold exposure of strawberry, integrative “omic” approaches were applied to F. ananassa ‘Korona’. Analysis of leaf tissue was emphasized because of its immediate and early responses in the cold acclimation processes. Levels of metabolites, proteins, and transcripts in tissues from plants grown at 20°C were compared to those following 1 to 10 days of cold exposure. When leaves and roots were subjected to GC/TOF-MS-based metabolite profiling, about 160 compounds comprising mostly structurally annotated primary metabolites and secondary metabolites, were found. Overall, ‘Korona’ showed a modest increase of protective metabolites such as amino acids (aspartic acid, leucine, isoleucine, and valine), pentoses, phosphorylated and non-phosphorylated hexoses, and distinct compounds of the raffinose pathway (galactinol and raffinose). Distinctive responses were observed in roots and leaves. By 2DE proteomics a total of 845 spots were observed in leaves; 4.6% changed significantly in response to cold. Twenty-one proteins were identified, many of which were associated with general metabolism or photosynthesis. Transcript levels in leaves were determined by microarray, where dozens of cold associated transcripts were quantitatively characterized, and levels of several potential key contributors (e.g., the dehydrin COR47 and GADb) to cold tolerance were confirmed by qRT-PCR. Cold responses are placed within the existing knowledge base of low temperature stress change in plants, allowing an evaluation of the uniqueness or generality of Fragaria responses in photosynthetic tissues. Overall, the cold response characteristics of ‘Korona’ are consistent with a moderately cold tolerant plant.

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The woodland strawberry (Fragaria vesca) has become the model plant for the economically important, but genetically complex, octoploid F. × ananassa. Crown rot caused by the oomycete Phytophthora cactorum is a major problem for the strawberry industry and the identification and incorporation of efficient resistance genes into superior cultivars are important for breeding. In the present study, two experimental populations were used in inoculation experiments under controlled greenhouse condition. Studies of a sparse diallel cross between resistant and susceptible F. vesca genotypes concluded that resistance to crown rot is inherited as a dominant trait under nuclear control. Subsequently, an F2 population derived from the grandparents Bukammen (resistant) and Haugastøl 3 (susceptible) collected in Norway, were phenotyped in infection experiments and genotyped using genotyping-by-sequencing. A 416.2-cM linkage map was constructed, and a single major gene locus was identified on linkage group 6 that we attributed to resistance to Phytopthora infection. We propose to name the resistance locus RPc-1 (Resistance to Phytophthora cactorum 1). Gene prediction of the 3.3 Mb QTL recovered 801 genes of which 69 had a potential role in plant disease resistance.

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The winter hardiness of strawberry varieties used in perennial production systems varies greatly. Still, little information is available on how plant metabolism adapts to cold and freezing temperatures under natural temperature and light conditions. In order to examine the hardening process of overwintering meristematic tissue in Fragaria  ananassa, crown samples of field-grown var. ‘Polka’ and ‘Honeoye’ were consecutively collected over a period of 15 weeks, i.e. from the end of the season (week 35/ end August) until midwinter (week 50/ December). Samples were subjected to qGC MS metabolite profiling to assess the reconfiguration of central metabolism, and characterize the regulation of selected compatible solutes. Besides changes in amino acid patterns (glutamic acid, aspartic acid, and asparagine), monosaccharide levels (fructose) increased strongly in ‘Honeoye’ (180 fold compared to start control) towards the end of the acclimation period. In contrast, ‘Polka’ showed a concentration peak (36-fold) in week 47 and a decline towards week 50. Also sucrose levels were steadily increased throughout the cold hardening period with averagely 6-fold higher levels in ‘Honeoye’ compared to ‘Polka’, thus underscoring cultivar-dependent differences. However, both varieties showed a decline in sucrose levels after week 47. Particularly, the raffinose pathway was affected leading to strongly and transiently increased levels of the precursor galactinol (week 42/ mid-October) and the trisaccharide raffinose (weeks 43 to 47/ end October to mid-November). While galactinol biosynthesis was earlier induced in ‘Polka’ (week 38) compared to ‘Honeoye’ (week 39), subsequent raffinose production was delayed in ‘Polka’ (week 47) compared to ‘Honeoye’ (week 45). Major metabolic changes in both varieties coincided with a decrease in day length below 14 h in mid-September, and a consistent drop below 10°C average day temperature by the end of September.

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The use of artificial freezing tests, identification of biomarkers linked to or directly involved in the low-temperature tolerance processes, could prove useful in applied strawberry breeding. This study was conducted to identify genotypes of diploid strawberry that differ in their tolerance to low-temperature stress and to investigate whether a set of candidate proteins and metabolites correlate with the level of tolerance. 17 Fragaria vesca, 2 F. nilgerrensis, 2 F. nubicola, and 1 F. pentaphylla genotypes were evaluated for low-temperature tolerance. Estimates of temperatures where 50 % of the plants survived (LT50) ranged from −4.7 to −12.0 °C between the genotypes. Among the F. vesca genotypes, the LT50 varied from −7.7 °C to −12.0 °C. Among the most tolerant were three F. vesca ssp. bracteata genotypes (FDP821, NCGR424, and NCGR502), while a F. vesca ssp. californica genotype (FDP817) was the least tolerant (LT50 −7.7 °C). Alcohol dehydrogenase (ADH), total dehydrin expression, and content of central metabolism constituents were assayed in select plants acclimated at 2 °C. The LT50 estimates and the expression of ADH and total dehydrins were highly correlated (r adh = −0.87, r dehyd = −0.82). Compounds related to the citric acid cycle were quantified in the leaves during acclimation. While several sugars and acids were significantly correlated to the LT50 estimates early in the acclimation period, only galactinol proved to be a good LT50 predictor after 28 days of acclimation (r galact = 0.79). It is concluded that ADH, dehydrins, and galactinol show great potential to serve as biomarkers for cold tolerance in diploid strawberry.

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A crucial consideration for strawberry producers in Norway and other northern countries is winter freezing damage. A long-term goal of the Norwegian strawberry breeding is to increase winter hardiness and to improve fruit quality. Due to the complexity involved in regulating and enhancing freezing tolerance, the progress in the improvement of cultivars using traditional screening methods have had limited success. Thus, the development of molecular markers for freezing hardiness would facilitate the selection work for this trait. In this effort, we have developed and adopted state-of-art molecular tools to investigate cold response in strawberry plants during the acclimation phase resulting in the identification of a large number of genes, proteins, and distinct metabolites that correspond to cold/freezing tolerance in strawberry. To identify proteins responsible for freezing tolerance in strawberry we have examined alterations in protein levels in strawberry varieties that differ in cold tolerance using either 2-DE gel analysis followed by LC-MS/MS analysis or a shotgun MS/MS approach. Proteomic analysis suggested 30 potential biomarkers that showed significant changes in the cultivated strawberry in response to cold. In addition, GC-MS-based metabolite profiling revealed the up-regulation of carbohydrates, polyols, amino acids, TCA intermediates, and other distinct secondary metabolites after cold treatment. Transcriptional analysis of the cold acclimated samples also confirmed the regulation upon cold-treatment with varietal differences in strawberry. Moreover, several F2-populations from the model F. vesca parents diverging in cold tolerance have been developed in order to facilitate mapping of QTLs by performing GBS analyses. The knowledge attained from these endeavors is expected to expedite breeding of strawberries to achieve freezing tolerant lines and provide an integrative understanding of the molecular pathways that underlie this characteristic. * Rohloff et al. (2012) Metabolite profiling reveals novel multi-level cold responses in the model Fragaria vesca. Phytochemistry 79:99-109. * Koehler et al. (2012) Proteomic study of low temperature responses in strawberry cultivars (Fragaria x ananassa) that differ in cold tolerance. Plant Physiology 159:1787–1805 * Davik et al., (2012) Low temperature tolerance in diploid strawberry species (Fragaria ssp.) and its correlation to alcohol dehydrogenase levels, dehydrin levels, and central metabolism constituents. Planta (in press; DOI: 10.1007/s00425-012-1771-2).

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The winter hardiness of strawberry cultivars used in perennial production systems varies greatly, although a strong linkage exists between transcriptional and metabolic changes during cold acclimation. Still, little information is available on how plant metabolism adapts to cold and freezing temperatures under natural temperature and light conditions. In order to examine the hardening process of overwintering meristematic tissue in Fragaria x ananassa, crown samples of field-grown cvs. ‘Polka’ and ‘Honeoye’ were consecutively collected over a period of 15 weeks, i.e. from the end of the season (week 35/ end August) until midwinter (week 50/ December). Samples were subjected to qGC MS metabolite profiling to assess the reconfiguration of central metabolism, and characterize the regulation of selected compatible solutes (amino acids, Krebs metabolites, sugars, polyols). Besides changes in amino acid patterns (glutamic acid, aspartic acid, and asparagine), monosaccharide levels (fructose) were strongly enhanced until the end of the acclimation period in cv. ‘Honeoye’ (180-fold compared to start control). In contrast, ‘Polka’ showed a concentration peak (36-fold) in week 47 and a decline towards week 50. Also sucrose levels were steadily enhanced throughout the cold hardening period with averagely 6-fold higher levels in ‘Honeoye’ compared to ‘Polka’, thus underscoring cultivar differences. However, both cultivars showed a clear decline in sucrose levels after week 47. Particularly, the raffinose pathway was affected leading to strongly and transiently increased levels of the precursor galactinol (week 42/ mid October) and the trisaccharide raffinose (weeks 43 to 47/ end October to mid November). While galactinol biosynthesis was obviously earlier induced in cv. ‘Polka’ (week 38) compared to ‘Honeoye’ (week 39), subsequent raffinose production and concentration peaks were clearly delayed in ‘Polka’ (week 47) in contrast to ‘Honeoye’ (week 45). Major metabolic changes in both cultivars coincided with a decrease in daylength below 14 h after week 37 (mid September), and a consistent drop below 10°C average day temperature in week 39 (end September). The effect of temperature and light conditions on metabolic cold acclimation in field-grown strawberry is discussed. Keywords: Winter hardiness, metabolite profiling, quadrupole gas chromatography-mass spectrometry (qGC-MS), temperature, light

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Winter freezing damage is a crucial factor in overwintering crops such as the octoploid strawberry (Fragaria × ananassa Duch.) when grown in a perennial cultivation system. Our study aimed at assessing metabolic processes and regulatory mechanisms in the close-related diploid model woodland strawberry (Fragaria vesca L.) during a 10-days cold acclimation experiment. Based on gas chromatography/ time-of-flight-mass spectrometry (GC/TOF-MS) metabolite profiling of three F. vesca genotypes, clear distinctions could be made between leaves and non-photosynthesizing roots, underscoring the evolvement of organ-dependent cold acclimation strategies. Carbohydrate and amino acid metabolism, photosynthetic acclimation, and antioxidant and detoxification systems (ascorbate pathway) were strongly affected. Metabolic changes in F. vesca included the strong modulation of central metabolism, and induction of osmotically-active sugars (fructose, glucose), amino acids (aspartatic acid), and amines (putrescine). In contrast, a distinct impact on the amino acid proline, known to be cold-induced in other plant systems, was conspicuously absent. Levels of galactinol and raffinose, key metabolites of the cold-inducible raffinose pathway, were drastically enhanced in both leaves and roots throughout the cold acclimation period of 10 days. Furthermore, initial freezing tests and multifaceted GC/TOF-MS data processing (Venn diagrams, Independent Component Analysis, Hierarchical Clustering) showed that changes in metabolite pools of cold-acclimated F. vesca were clearly influenced by genotype.

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Freezing damage is a crucial factor in the cultivation of perennial crops. Overwintering plants acclimate to decreasing temperatures in their environment and thus, prevent freezing damage of plant tissue. To assess transcriptional and metabolic changes in meristematic tissue (crowns) of octoploid strawberry (Fragaria × ananassa Duch.), acclimation experiments were carried out at above-zero temperature (2 °C) using three cultivars with contrasting cold tolerance: ‘Elsanta’ < ‘Frida’ < ‘Jonsok’. Crowns were sampled after 1 day (d), 2d, 2 weeks (w) and 6w in order to detect short- and long-term metabolic shifts. GC/MS-based metabolite profiling revealed more than 140 metabolites (identified structures, not-annotated mass spectral tags, and unidentified metabolites). Transcriptional changes were assessed at two time points (2d and 6w) using a customized Fragaria microarray chip developed as a joint collaboration between Graminor Breeding Ltd. and NTNU. A total of 4061 differentially regulated transcripts (unique 60-mer probes) with a p-value≤0.05 were detected in all hybridizations. Microarray analysis revealed the up-regulation of ~100 cold-responsive transcripts (TFs and dehydrins), also including enzymes involved in starch breakdown and raffinose biosynthesis. Gene-metabolite correlation analysis revealed strong connectivity in components of Krebs-cycle (citric and succinic acid), amino acids (isoleucine, aspartic acid, glutamic acid, valine and phenylalanine) and the raffinose pathway. Metabolite levels of hexoses (fructose and glucose), trisaccharides (raffinose), amino acids (aspartic acid, alanine and serine), phenols (gallic acid) and several polyphenols still increased during long-term acclimation phase. Varietal differences could be clearly explained by Venn diagrams: frost-tolerant ‘Jonsok’ showed least individual up- or down-regulated transcripts (2 d), and least commonly shared transcripts with frost-sensitive ‘Elsanta’ (2d and 6w). Further multivariate statistics and network analyses underscored genotype-dependent cold responses, and might further guide in the identification of frost-tolerant vs. sensitive plants in diverse Fragaria accessions or cross-breeding populations .

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Rotstokkråte i jordbær ble første gang rapportert i Norge i 1992 og siden er den blitt funnet på mer enn 100 steder over hele landet. Sykdommen forårsakes av Phytophthora cactorum og karakteriseres ved at unge blader visner raskt og hele planten visner i løpet av noen dager. I løpet av en sesong kan opptil 40 % av plantene dø. P. cactorum smitter plantene gjennom rothårene ved hjelp av svermesporer (zoosporer). Sykdommen starter oftest i fuktige områder av et felt siden sporene trenger vann for å bevege seg. Når en først har fått smitten i jorda er det vanskelig å bli kvitt den siden P. cactorum danner hvilesporer som kan overleve i flere år. Ulike jordbærsorter har ulik grad av mottakelighet for sykdommen. De mest brukte kommersielle sortene er dessverre mottakelige for sykdommen. Resistensegenskaper kan styres av ett eller flere gener og man kan derfor foredle fram resistente sorter. Tradisjonell foredling er tidkrevende og overføringa av resistens til en mottakelig sort vil kreve gjentatte tilbakekrysninger slik at man ikke mister alle de positive egenskapene til denne sorten. Ved å utvikle genetiske kart med markører for resistens kan man teste planter raskere og slik komme raskere fram til en resistent sort. Kunnskap om hvor mange resistensgener som er involvert i kampen mot skadegjøreren, når disse blir slått på og hvilke proteiner disse lager er også viktig. Når en skadegjører angriper en plante lager den bl.a. proteiner som bryter ned plantecelleveggen og svekker plantens immunforsvar. Planten på sin side lager resistensproteiner som gjenkjenner proteinene laget av skadegjøreren. Denne gjenkjennelsen setter i gang en forsvarsrespons hos planten. Resistensproteinene kodes for av resistensgener (R-gener). De fleste kjente R-genene inneholder en kort bestemt nukleotidsekvens. Dette fellestrekket gjør jakten på resistensgener enklere. I jakten på resistensgener i jordbær har vi valgt å arbeide med markjordbær (Fragaria vesca) istedenfor kommersielle jordbær (Fragaria x ananassa Duch.). Markjordbær er diploid og egner seg derfor godt for molekylærbiologiske studier. For å isolere R-gener og studere hvordan de ble uttrykt ble en mottakelig kultivar og en resistent kultivar smittet med zoosporer. Vevsprøver ble høstet i en tidsserie fra tid 0 (kontroll før smitting) til maksimum 8 dager etter smitting. Resultatet så langt viser at vi har isolert fragmenter fra mange ulike resistensgener og at disse blir uttrykt gjennom hele tidsrommet fra smitting til 8 dager etterpå.

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In order to support functional genomics research in octoploid (Fragaria x ananassa Duch.) and diploid (F. vesca) strawberry, a customized Fragaria microarray chip was developed as a joint collaboration between Graminor Breeding Ltd. and NTNU. F. vesca cDNA sequences were provided by The Center for Genomics and Bioinformatics, Indiana University (an assembly of >3 million reads from GS-FLX Titanium - Roche/454 Life Sciences sequencing), and about 59,000 publicly available Fragaria EST sequences were uploaded from NCBI. In addition, ~190 Mb of preliminary draft genome sequences from F. vesca were provided by the Strawberry Genome Sequencing Consortium (courtesy to V. Shulaev). cDNAs used as templates for probe design were validated by BlastN against the F. vesca draft genome excluding cDNAs of microbial origin. Genes not represented in the cDNA collection were identified by screening F. vesca draft genome against protein sequences from Arabidopsis thaliana, Vitis vinifera, Ricinus communis and Populus trichocarpa. Exon sequences from genes not found in the cDNAs were included. In total, 43723 unique 60-mer probes were designed and the Agilent eARRAY tool was used to produce a 4x44k format microarray chip. Fragaria chip applicability and feasibility for transcriptional profiling was investigated using either abiotic (low temperature) or biotic (pathogenic fungi) stress treatment. Microarray data will be subsequently integrated with other omics data to address gene-regulatory networks and biological functions. Cold acclimation experiments were focused on short- and long-term effects in meristematic tissue, and revealed the up-regulation of ~100 cold-responsive genes (transcription factors, dehydrins, enzymes), and transcripts involved in starch breakdown and raffinose biosynthesis. Beside central metabolism, secondary metabolism was also strongly modulated as seen by changes in the expression of flavonoid biosynthesis-related genes. Time-course studies of transcriptional responses in F. vesca accessions showing contrasting resistance toward the pathogen Phytophthora cactorum are in progress, and will be presented in-depth.

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Phytophthora cactorum, den sopp-lignende skadegjøreren som forårsaker kronråte i jordbær, kan overleve i mange år i jorda og det er ingen god måte å bli kvitt skadegjøreren på når den har kommet inn i et felt eller en planteskole. Smittede planter trenger ikke umiddelbart å vise symptomer, noe som gjør skadegjøreren enda mer vanskelig å hanskes med. Selv om det er variasjon i mottakelighet, er så godt som alle jordbærsorter i kommersiell bruk, mottakelige. Vi vet imidlertid at resistente varianter finnes innenfor jordbæras nære slektninger, foreldreartene Fragaria virginiana og Fragaria chiloensis. Det er mye uklarhet omkring hva som ligger bak forskjeller i kronråteresistens, og siden en slik forståelse er viktig for håndteringen i en foredlingssammenheng, ønsker vi å undersøke dette. Jordbæra (Fragaria x ananassa) og dens nevnte foreldrearter er imidlertid oktoploide - de har 8 sett kromosomer - noe som gjør dem vanskelig å bruke i genetiske studier. Vi, og mange andre forskergrupper, har derfor valgt å fokusere på en enklere modellplante for å finne basiskunnskap som vi i ettertid håper å kunne overføre til de dyrkede jordbæra.

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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.  

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Crown rot caused by Phytophthora cactorum is an important disease in commercial strawberry production worldwide. The level of resistance varies greatly between cultivars, and many of the most commonly grown cultivars are quite susceptible to P. cactorum. Adequate soil drainage, clean planting material and use of highly resistant cultivars are the most important measures against crown rot. Previous work at our institute has involved evaluation of methods to screen for resistance, cultivar and progeny screening, and use of induced resistance against the disease. That work also included a genetic study of P. cactorum isolates from various host plants and different geographic origins. P. cactorum has many host plants, but it turned out that isolates causing crown rot of strawberry differs genetically from those with other host origin. A project was recently initiated, where one of the main goals has been to identify molecular markers for resistance against P. cactorum in strawberry. Genotypes of diploid Fragaria species have been screened for resistance, and the progeny from a cross between a susceptible and a resistant genotype will be evaluated by the end of this year. Commercially grown strawberry is very heterozygous and octoploid. Diploid Fragaria species are therefore useful as model organisms. The Fragaria genus has a conserved organisation, and hopefully information obtained from the study of diploid genotypes can be transferred to cultivated Fragaria x ananassa and possibly to other important crop plants in Rosaceae.

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BackgroundThe cultivated strawberry Fragaria ×ananassa is one of the most economically-important soft-fruit species. Few structural genomic resources have been reported for Fragaria and there exists an urgent need for the development of physical mapping resources for the genus. The first stage in the development of a physical map for Fragaria is the construction and characterisation of a high molecular weight bacterial artificial chromosome (BAC) library.MethodsA BAC library, consisting of 18,432 clones was constructed from Fragaria vesca f. semperflorens accession "Ali Baba". BAC DNA from individual library clones was pooled to create a PCR-based screening assay for the library, whereby individual clones could be identified with just 34 PCR reactions. These pools were used to screen the BAC library and anchor individual clones to the diploid Fragaria reference map (FV×FN).FindingsClones from the BAC library developed contained an average insert size of 85 kb, representing over seven genome equivalents. The pools and superpools developed were used to identify a set of BAC clones containing 70 molecular markers previously mapped to the diploid Fragaria FV×FN reference map. The number of positive colonies identified for each marker suggests the library represents between 4× and 10× coverage of the diploid Fragaria genome, which is in accordance with the estimate of library coverage based on average insert size.ConclusionThis BAC library will be used for the construction of a physical map for F. vesca and the superpools will permit physical anchoring of molecular markers using PCR.

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Vi studerer to sykdommer forårsaket av Phytophthora, rotstokkråte i jordbær (P. cactorum) og rød rotråte i bringebær (P. fragariae var. rubi (Pfr)). Bringebær og jordbær sorter varierer i resistens, men de fleste kommersielle kultivarene er mottakelige for disse to sykdommene. En universell merkemetode ble brukt for å gjøre markøranalyse for å identifisere genetiske markører koblet til resistens. For bringebær er populasjonen brukt for kartlegging avkommene fra en krysning mellom resistent Asker og mottakelig Glen Moy. Resistensen til 200 avkom har blitt testet under kontrollerte betingelser med smitting i vannkultur. Tretti dager etter inokulering med mycel av Pfr ble grad av symptom registrert. Kommersielt dyrket jordbær er en svært heterozygot oktoploid. Vi bruker derfor diploid villjordbær som en modellplante. Bioforsk har en samling av diploide jordbærgenotyper fra ulike steder i Norge. Totalt har 68 genotyper blitt testet for deres resistens mot P. cactorum. Ulik grad av resistens har blitt observert. Mottakelige så vel som svært resistente aksesjoner har blitt identifisert. Basert på disse resultatene vil genotyper bli valgt for å lage en segregerende populasjon fra en resistent x mottagelig krysning for å studere nedarvingen av P. cactorum resistensen.

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Vi studerer to sykdommer forårsaket av Phytophthora, rotstokkråte i jordbær (P. cactorum) og rød rotråte i bringebær (P. fragariae var. rubi (Pfr)). Bringebær og jordbær sorter varierer i resistens, men de fleste kommersielle kultivarene er mottakelige for disse to sykdommene. En universell merkemetode ble brukt for å gjøre markøranalyse for å identifisere genetiske markører koblet til resistens. For bringebær er populasjonen brukt for kartlegging avkommene fra en krysning mellom resistent Asker og mottakelig Glen Moy. Resistensen til 200 avkom har blitt testet under kontrollerte betingelser med smitting i vannkultur. Tretti dager etter inokulering med mycel av Pfr ble grad av symptom registrert. Kommersielt dyrket jordbær er en svært heterozygot oktoploid. Vi bruker derfor diploid villjordbær som en modellplante. Bioforsk har en samling av diploide jordbærgenotyper fra ulike steder i Norge. Totalt har 68 genotyper blitt testet for deres resistens mot P. cactorum. Ulik grad av resistens har blitt observert. Mottakelige så vel som svært resistente aksesjoner har blitt identifisert. Basert på disse resultatene vil genotyper bli valgt for å lage en segregerende populasjon fra en resistent x mottagelig krysning for å studere nedarvingen av P. cactorum resistensen.

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Tilnærminger gjennom foredling og bioteknologi blir fortløpende brukt for å øke innholdet av spesifike bioaktive komponenter i planter, men å styre plantemetabolismen slik at man forbedrer produktene er fremdeles vanskelig. Det er imidlertid en økende klarhet i at multiple gen- og omgivelses-faktorer påvirker produksjon og akumulering av bioaktive forbindelser, men disse forholdene er skjelden med i bildet når f.eks bær blir markedsført.

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Total anti-oxidant capacity (TAC) and the contents of mono- and disaccharides, and organic acids were determined in strawberry fruit from ten genotypes sampled from eight experimental sites in Norway in 2002 and 2003.The difference between genotypes was significant for all recorded traits, and it appeared possible to select for all traits in breeding programmes. On average, the Norwegian bred cultivar `Carmen" had a TAC of 30.07 mmol kg"1 fresh weight (FW), compared to 23.16 mmol kg"1 FW in the standard cultivar `Korona". TAC was negatively correlated with fruit size, rainfall and leaf surface humidity, but was positively correlated with the minimum temperature on the day prior to sampling. Mono- and di-saccharide contents were negatively correlated with both minimum and maximum temperatures, and with wind velocity. It was confirmed that the sugars:organic acids ratio was inversely related to the maximum temperature on the day before harvest, which supports anecdotal claims that strawberries grown in northern areas have, on average, better flavour.

Sammendrag

Et prosjekt for utprøving av jordbærsorter ved Bioforsk Midt-Norge i perioden 2006-2008, blir delvis finansiert av Trønderfrukt og FMLA Nord-Trøndelag. I 2006 ble det følgelig plantet et sortsfelt som vil bli høstet i 2007 og 2008. I tillegg ble det i 2006 høstet i avanserte foredlingsfelter og sortsforsøk som var plantet i 2004 og 2005. Resultatene som rapporteres her er fra felter som er plantet i 2004 og 2005. I den perioden var arbeidet delvis finansiert av FMLA Nord-Trøndelag og Graminor AS. Det er vanskelig å se at noe av det nye sortsmaterialet som ble plantet i 2005, kan konkurrere med standardsortene (Korona og Polka). Frida som er svært produktiv og som også smaker godt, blir fort veldig nedsmittet av meldugg på bærene. Muligens yter det dyrkingssystemet vi benytter Frida urettferdighet. Sortene Babette og Hanibal produserer godt, men har ikke den gode smaken som standardsortene har. Seleksjonen PK98.204 (navneforslag: Iris) har også mange svært fine attributter, men når muligens ikke helt opp på grunn av smakskvalitetene. Av nytt sortsmateriale som er utviklet ved Kvithamar på oppdrag fra Graminor, er seleksjonen PK00.335 interessant. Dette er en kryssing mellom Polka og Marmolada og som har vist seg fram med god avling, store bær og fått gode subjektive vurderinger. Den er en sort for hovedsesongen og må derfor konkurrere med Korona og Polka – noe den synes å klare vurdert ut fra tilgjengelig datamateriale. Imidlertid er det nødvendig med flere forsøk før eventuell oppformering starter. Utprøving i mindre skala hos dyrkere burde imidlertid settes i gang.

Sammendrag

A mixed model approach was used to estimate variance components and heritabilities for resistance to powdery mildew, a wind-borne disease in strawberry. In order to improve precision in the statistical computations, spatial error control effects were included to account for systematic environmental variations in the large field trials. Pedigree information was included where feasible. Seedling families obtained from an incomplete 63-by-63 diallel cross were grown at six locations and scored subjectively for mildew attack three times during the growing season. The 63 parents included both European and American cultivars as well as advanced selections from various breeding programmes. A total of 298 full-sib families were realized, including 26 reciprocal families. No reciprocal differences were found. On a plot-mean basis, the broad-sense heritability was found to be intermediate, H2=0.44"0.50, depending on whether the pedigree information was included in the model or not. The increase was mainly due to a substantial increase in the additive variance component. Likewise, the narrow-sense heritability increased from h2=0.39 to h2=0.45 when the pedigree information was included, while the ratio of the specific combining ability variance to the general combining ability variance fell from 13% to 10%. The predicted breeding values of the 63 parents demonstrate that important cultivars such as Elsanta and Korona are unlikely to produce progenies with a high degree of resistance. On the other hand, the Norwegian cultivar Solprins, the Canadian cultivar Kent and the Italian cultivar Patty appeared to give highly resistant progeny. At the full-sib level, the estimated disease scores ranged from 1.15 (Kent × Induka) to 4.19 (Cavendish × Avanta), revealing a huge range of variation for powdery mildew resistance available for selection.

Sammendrag

Resultat frå jordbærforedling i Planteforsk vert presentert. Fire sortar frå prosjektet er gitt namn. Dei mest lovande av desse ser ut til å vere `Babette" og `Hanibal". `Babette" konkurrerer godt med `Honeoye" i tidlegsegmentet. `Babette" har litt høgare avling enn `Honeoye", større bær og skårer betre på kvalitetseigenskaper ved bæret og den er også sterkare mot mjøldogg på planta. `Hanibal" har omlag samme avlingsprofil som `Korona" og `Polka" og skil seg frå desse med betre bærkvalitet. Spesielt skalstyrke, fastheit og heilskapen er betre, samstundes som den skårer minst like bra på smak. Tre nye seleksjonar vert omtala. PK98.12 er aktuell for hovedsesongen medan PK98.204 er aktuell for tidlegsesongen. PK98.204 produserer vesentleg betre enn `Honeoye" samstundes som den har betre bærkvalitet og smak. PK98.12 skil seg frå `Korona" spesielt på bærstorleik og ytre kvalitetseigenskaper. PK97.48.1 har etter utprøving hos prøvedyrkarar kome i fokus som ein mogeleg industrisort. I våre eigne forsøk har PK97.48.1 vore produktiv, men noko småfallen samenlikna med til dømes `Korona". Til konsumbær har den difor falle igjennom. Seleksjonen har imidlertid svært gode konserveseigenskaper.

Sammendrag

Seleksjonen PK97.48.1 har vist seg å ha flere gode egenskaper som råstoff for industrien, og den kan kanskje komme til å erstatte den gamle sorten "Senga Sengana". Videre utprøvinger vil vise dette, men så langt har resultatene vært lovende.

Sammendrag

Utbrot av rotstokkròte i jordbær har i stor grad samanheng med sortane som vert dyrka. Utviklinga dei siste tiåra har gått mot meir mottakelege sortar, og dette er hovudårsaka til den sterke spreiinga av sjukdomen. Ved Planteforsk har ei stor mengde sortar vortne testa dei siste åra, og også nedarving av motstandsevne mot sjukdomen har vorte studert.

Sammendrag

Aurora" og "Carmen" bør prøves i begrenset omfang hos dyrkere før den eventuelt oppformeres for alminnelig salg. "Polka" ser ut til å være mer produktiv enn "Korona", men det er en ulempe at "Polka" etter hvert utvikler en lite tiltalende plante. Verdiprøvingsfeltene på Kise har vist at "Korona" holder stand der. To nye sorter "Florence" og "Frida" kan imidlertid vise seg som utfordrere. "Florence" har blitt godt mottatt i forbrukertester, mens "Frida" ser ut til å være meget produktiv. Mer erfaring vil nok akkumuleres fra disse sortene etter hvert. Fra jordbærforedlingen i Planteforsk ligger de an til at fire nummersorter vil bli oppformert for begrenset utprøving.

Sammendrag

Jordbærdyrking i Nord-Norge stiller store krav til sortsmaterialet. Vanskelige overvintringsforhold og korte, kjølige og våte somre opptreder opptrer i mer ekstrem grad enn i sør. For å sikre årviss produksjon trenger vi nye sorter, som har bedre overvintringsevne og som har faste bær, som tåler både regn, fuktighet, håndtering og transport. Hovedsorter i Nord-Norge er "Zefyr" og "Korona". "Glima" er en populær tidligsort. "Polka" er på vei frem. I artikkelen gis en oversikt over styrker og svakheter for disse og andre aktuelle sorter for Nord-Norge. Nytt sortsmateriale fra Planteforsk sitt foredlingsprogram er på vei ut til dyrkerne. To sorter; "Carmen" og "Aurora" er nu under verdiprøving. Av disse har Carmen gitt gode resultater i forsøksfelt på Planteforsk Vågønes/ Bodø, mens Aurora viste svak overvintring og gav dårlig utbytte. Ytterligere seks lovende kloner et uttatt til videre utprøving.

Sammendrag

During a period of five years (1998 - 2002), 26 strawberry cvs and 5 selections were tested for resistance to crown rot. Cold stored plants inoculated with zoospores of Phytophthora cactorum were used in all experiments. The results showed that resistance to P. cactorum vary greatly between cvs, and the most resistant ones were Senga Sengana, Induka, Melody, Glima, and Bogota, while the most susceptible were Tamella, Inga, Evita and Jonsok. The results were compared to those obtained by other authors, and there were clear indications that the genetic background affects the degree of susceptibility to P. cactorum. Many of the most resistant cvs descend from Senga Sengana (e.g. Bounty, Glima, Induka and Melody), and several of the most susceptible cvs have common parentage (e.g. Inga, Tamella, Elsanta and Evita). In a resistance test of the progeny from two separate crosses between a resistant and a susceptible cv. 61 and 65 % of the offspring were intermediately to very susceptible, and 17 and 13 % were resistant at the level of Senga Sengana. Hence, there is a high risk of losing offspring with high levels of resistance if selection for resistance to crown rot is not performed at an early stage in a breeding programme.

Sammendrag

En rapport om status i Planteforsks jordbærforedling ved utgangen av 2000. De mest lovende nummersortene presenteres. Resultatene fra 1999 ble i stor grad bekreftet i 2000 og dette er lovende med tanke på lansering av nye sorter i jordbær .

Sammendrag

En presentasjon av jordbærforedlingen i Planteforsk. Det gis også en kort presentasjon av de mest lovende seleksjonsmaterialet per sommeren 1999.

Sammendrag

En oversikt over jordbærproduksjonen i de nordiske landene. Det er lagt vekt på de spesiell problemene og mulighetene som jordbærdyrkingen har i disse landene.

Sammendrag

Two inbred rapeseed lines differing in aliphatic glucosinolate content and the reciprocal hybrids between them were grown under greenhouse conditions until seed maturity at three levels of sulphur supply. Heterosis was confirmed for seed yield and yield related traits irrespective of sulphur supply. Seeds harvested from the F1-hybrid plants were all high in aliphatic glucosinolates. The line low in aliphatic glucosinolates yielded seeds that were lower in methionine and cysteine than the other genotypes did at all levels of sulphur supply. It was, however, not more severely affected by suboptimal supply than the line high in glucosinolates