SummaryImproving tolerance to ethylene‐induced early senescence of flowers and fruits is of major... more SummaryImproving tolerance to ethylene‐induced early senescence of flowers and fruits is of major economic importance for the ornamental and food industry. Genetic modifications of genes in the ethylene‐signalling pathway have frequently resulted in increased tolerance but often with unwanted side effects. Here, we used CRISPR/Cas9 to knockout the function of two CpEil1 genes expressed in flowers of the diploid ornamental plant Campanula portenschlagiana. The ethylene tolerance in flowers of the primary mutants with knockout of only one or all four alleles clearly showed increased tolerance to exogenous ethylene, although lower tolerance was obtained with one compared to four mutated alleles. The allele dosage effect was confirmed in progenies where flowers of plants with zero, one, two, three and four mutated alleles showed increasing ethylene tolerance. Mutation of the Cpeil1 alleles had no significant effect on flower longevity and endogenous flower ethylene level, indicating tha...
Barley (Hordeum vulgare L. cv. Digger) was grown for 22 d in enclosed chambers with a C02 enrichm... more Barley (Hordeum vulgare L. cv. Digger) was grown for 22 d in enclosed chambers with a C02 enrichment of 35, 155, 400 or 675/?mol C02 mol'1. C02 enrichment increased photosynthetic capacity in the plants grown at either of the two highest levels of pC02. A C02 enrichment of 675 //mol C02 caused a significant increment of shoot dry weight, whereas no changes were observed in fresh weight, chlorophyll or protein levels. At a light intensity of 860//mol m'2s~1 C02 enrichment caused photosynthetic capacity to increase by 250%, whereas no effect was observed at 80 //mol m~2 s~1. Over time, photosynthesis decreased by 70% independent of C02. A time-dependent increase in the level of extractable fructose was observed whereas total extractable carbohydrate only changed slightly.
This study provides an immunohistochemical demonstration of the involvement of the ubiquitin- and... more This study provides an immunohistochemical demonstration of the involvement of the ubiquitin- and proteasome-dependent pathway during differentiation and organogenesis in plants. The localisation of ubiquitin and the proteasome was studied in meristems, leaves, stems and roots of sunflower (Helianthus annuus L. cv. Giganteus). By using a new technique that enhances very low antigen signals, we obtained information on the structural distribution of the ubiquitin- and proteasome-dependent pathway, and of the importance of this pathway during organogenesis and plant development. Ubiquitin and the proteasome showed overall similarities in their cellular localisation. The highest antigenic signal was observed in the root and shoot apical meristems, in leaf primordia and vascular tissue. The cambium showed less expression than the apical meristems. During adventitious root formation in cuttings, no sign of increased expression was observed within dedifferentiating tissue, but as organogenesis progressed, the antigenic signal of ubiquitin and the proteasome gradually increased in the developing roots. Comparison of immunochemical results and Western blots demonstrated that important changes in the cellular antigen signal could only be detected by immunochemistry.
Sugarcane mosaic virus (SCMV) is the causal pathogen for a severe mosaic virus disease of maize w... more Sugarcane mosaic virus (SCMV) is the causal pathogen for a severe mosaic virus disease of maize worldwide. In our previous research, the maize resistance gene analog (RGA) Pic19 and its three cognate BAC contigs were mapped to the same region as the SCMV resistance gene Scmv1. Here we report the isolation and characterization of the Pic19R gene family members from the inbred line FAP1360A, which shows complete resistance to SCMV. Two primer pairs were designed based on the conserved regions among the known Pic19 paralogs and used for rapid amplification of cDNA ends of FAP1360A. Six full-length cDNAs, corresponding to the Pic19R-1 to -6 paralogs, were obtained. Three of them (Pic19R-1 to -3) had uninterrupted coding sequences and were, therefore, regarded as candidates for the Scmv1 gene. A total of 18 positive BAC clones harboring the Pic19R-2 to -5 paralogs were obtained from the FAP1360A BAC library and assembled into two BAC contigs. Two markers, tagging Pic19R-2 and -3 and Pic19R-4, were developed and used to genotype a high-resolution mapping population segregating solely for the Scmv1 locus. Although closely linked, none of these three Pic19R paralogs co-segregated with the Scmv1 locus. Analysis of the Pic19R family indicated that the Pic19R-1 paralog is identical to the known Rxo1 gene conferring resistance to rice bacterial streak disease and none of the other Pic19R paralogs seems to be involved in resistance to SCMV.
The molecular mechanisms underlying the development and progression of sugarcane mosaic virus (SC... more The molecular mechanisms underlying the development and progression of sugarcane mosaic virus (SCMV) infection in maize are poorly understood. A study of differential expression was conducted to identify genes involved in resistance to SCMV. In this study, we combined suppression subtractive hybridization and macroarray hybridization to identify genes that are differently expressed in the near isogenic lines F7+ (SCMV resistant) and F7 (susceptible). Altogether, 302 differentially expressed genes were identified in four comparisons based on constitutively expressed and inducible genes, and on compatible and incompatible plant-virus interactions. Apart from genes related to metabolism, most of the functionally classified genes identified belonged to three pathogenesis-related categories: cell rescue, defense, cell death and ageing, signal transduction, and transcription. The latter three groups accounted for 56-66% of the genes classified. Some 19% (60 of 302) of the identified genes had previously been assigned to 29 bins distributed over all ten maize chromosomes. Among the mapped genes, 31% (18 of 58) were located within the Scmv2 and Scmv1 regions on chromosomes 3 and 6, respectively, which have been associated with resistance to SCMV. Promising candidate genes for Scmv1 have been identified, such as AA661457 (receptor-like kinase Xa21-binding protein 3). The implications of the genomic distribution of differentially expressed genes identified by this isogenic comparison are discussed in the context of breeding for resistance.
Cannabis sativa L. is an ancient crop used for fiber and seed production and not least for its co... more Cannabis sativa L. is an ancient crop used for fiber and seed production and not least for its content of cannabinoids used for medicine and as an intoxicant drug. Due to the psychedelic effect of one of the compounds, tetrahydrocannabinol (THC), many countries had regulations or bands on Cannabis growing, also as fiber or seed crop. Recently, as many of these regulations are getting less tight, the interest for the many uses of this crop is increasing. Cannabis is dioecious and highly heterogenic, making traditional breeding costly and time consuming. Further, it might be difficult to introduce new traits without changing the cannabinoid profile. Genome editing using new breeding techniques might solve these problems. The successful use of genome editing requires sequence information on suitable target genes, a genome editing tool to be introduced into plant tissue and the ability to regenerate plants from transformed cells. This review summarizes the current status of Cannabis bre...
SummaryImproving tolerance to ethylene‐induced early senescence of flowers and fruits is of major... more SummaryImproving tolerance to ethylene‐induced early senescence of flowers and fruits is of major economic importance for the ornamental and food industry. Genetic modifications of genes in the ethylene‐signalling pathway have frequently resulted in increased tolerance but often with unwanted side effects. Here, we used CRISPR/Cas9 to knockout the function of two CpEil1 genes expressed in flowers of the diploid ornamental plant Campanula portenschlagiana. The ethylene tolerance in flowers of the primary mutants with knockout of only one or all four alleles clearly showed increased tolerance to exogenous ethylene, although lower tolerance was obtained with one compared to four mutated alleles. The allele dosage effect was confirmed in progenies where flowers of plants with zero, one, two, three and four mutated alleles showed increasing ethylene tolerance. Mutation of the Cpeil1 alleles had no significant effect on flower longevity and endogenous flower ethylene level, indicating tha...
Barley (Hordeum vulgare L. cv. Digger) was grown for 22 d in enclosed chambers with a C02 enrichm... more Barley (Hordeum vulgare L. cv. Digger) was grown for 22 d in enclosed chambers with a C02 enrichment of 35, 155, 400 or 675/?mol C02 mol'1. C02 enrichment increased photosynthetic capacity in the plants grown at either of the two highest levels of pC02. A C02 enrichment of 675 //mol C02 caused a significant increment of shoot dry weight, whereas no changes were observed in fresh weight, chlorophyll or protein levels. At a light intensity of 860//mol m'2s~1 C02 enrichment caused photosynthetic capacity to increase by 250%, whereas no effect was observed at 80 //mol m~2 s~1. Over time, photosynthesis decreased by 70% independent of C02. A time-dependent increase in the level of extractable fructose was observed whereas total extractable carbohydrate only changed slightly.
This study provides an immunohistochemical demonstration of the involvement of the ubiquitin- and... more This study provides an immunohistochemical demonstration of the involvement of the ubiquitin- and proteasome-dependent pathway during differentiation and organogenesis in plants. The localisation of ubiquitin and the proteasome was studied in meristems, leaves, stems and roots of sunflower (Helianthus annuus L. cv. Giganteus). By using a new technique that enhances very low antigen signals, we obtained information on the structural distribution of the ubiquitin- and proteasome-dependent pathway, and of the importance of this pathway during organogenesis and plant development. Ubiquitin and the proteasome showed overall similarities in their cellular localisation. The highest antigenic signal was observed in the root and shoot apical meristems, in leaf primordia and vascular tissue. The cambium showed less expression than the apical meristems. During adventitious root formation in cuttings, no sign of increased expression was observed within dedifferentiating tissue, but as organogenesis progressed, the antigenic signal of ubiquitin and the proteasome gradually increased in the developing roots. Comparison of immunochemical results and Western blots demonstrated that important changes in the cellular antigen signal could only be detected by immunochemistry.
Sugarcane mosaic virus (SCMV) is the causal pathogen for a severe mosaic virus disease of maize w... more Sugarcane mosaic virus (SCMV) is the causal pathogen for a severe mosaic virus disease of maize worldwide. In our previous research, the maize resistance gene analog (RGA) Pic19 and its three cognate BAC contigs were mapped to the same region as the SCMV resistance gene Scmv1. Here we report the isolation and characterization of the Pic19R gene family members from the inbred line FAP1360A, which shows complete resistance to SCMV. Two primer pairs were designed based on the conserved regions among the known Pic19 paralogs and used for rapid amplification of cDNA ends of FAP1360A. Six full-length cDNAs, corresponding to the Pic19R-1 to -6 paralogs, were obtained. Three of them (Pic19R-1 to -3) had uninterrupted coding sequences and were, therefore, regarded as candidates for the Scmv1 gene. A total of 18 positive BAC clones harboring the Pic19R-2 to -5 paralogs were obtained from the FAP1360A BAC library and assembled into two BAC contigs. Two markers, tagging Pic19R-2 and -3 and Pic19R-4, were developed and used to genotype a high-resolution mapping population segregating solely for the Scmv1 locus. Although closely linked, none of these three Pic19R paralogs co-segregated with the Scmv1 locus. Analysis of the Pic19R family indicated that the Pic19R-1 paralog is identical to the known Rxo1 gene conferring resistance to rice bacterial streak disease and none of the other Pic19R paralogs seems to be involved in resistance to SCMV.
The molecular mechanisms underlying the development and progression of sugarcane mosaic virus (SC... more The molecular mechanisms underlying the development and progression of sugarcane mosaic virus (SCMV) infection in maize are poorly understood. A study of differential expression was conducted to identify genes involved in resistance to SCMV. In this study, we combined suppression subtractive hybridization and macroarray hybridization to identify genes that are differently expressed in the near isogenic lines F7+ (SCMV resistant) and F7 (susceptible). Altogether, 302 differentially expressed genes were identified in four comparisons based on constitutively expressed and inducible genes, and on compatible and incompatible plant-virus interactions. Apart from genes related to metabolism, most of the functionally classified genes identified belonged to three pathogenesis-related categories: cell rescue, defense, cell death and ageing, signal transduction, and transcription. The latter three groups accounted for 56-66% of the genes classified. Some 19% (60 of 302) of the identified genes had previously been assigned to 29 bins distributed over all ten maize chromosomes. Among the mapped genes, 31% (18 of 58) were located within the Scmv2 and Scmv1 regions on chromosomes 3 and 6, respectively, which have been associated with resistance to SCMV. Promising candidate genes for Scmv1 have been identified, such as AA661457 (receptor-like kinase Xa21-binding protein 3). The implications of the genomic distribution of differentially expressed genes identified by this isogenic comparison are discussed in the context of breeding for resistance.
Cannabis sativa L. is an ancient crop used for fiber and seed production and not least for its co... more Cannabis sativa L. is an ancient crop used for fiber and seed production and not least for its content of cannabinoids used for medicine and as an intoxicant drug. Due to the psychedelic effect of one of the compounds, tetrahydrocannabinol (THC), many countries had regulations or bands on Cannabis growing, also as fiber or seed crop. Recently, as many of these regulations are getting less tight, the interest for the many uses of this crop is increasing. Cannabis is dioecious and highly heterogenic, making traditional breeding costly and time consuming. Further, it might be difficult to introduce new traits without changing the cannabinoid profile. Genome editing using new breeding techniques might solve these problems. The successful use of genome editing requires sequence information on suitable target genes, a genome editing tool to be introduced into plant tissue and the ability to regenerate plants from transformed cells. This review summarizes the current status of Cannabis bre...
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Papers by Christina Ingvardsen