Viktor Voronin - Academia.edu (original) (raw)

Papers by Viktor Voronin

Research paper thumbnail of Evolutionary conservation and regulation of particular alternative splicing events in plant SR proteins

Nucleic Acids Research, 2006

Alternative splicing is an important mechanism for fine tuning of gene expression at the posttran... more Alternative splicing is an important mechanism for fine tuning of gene expression at the posttranscriptional level. SR proteins govern splice site selection and spliceosome assembly. The Arabidopsis genome encodes 19 SR proteins, several of which have no orthologues in metazoan. Three of the plant specific subfamilies are characterized by the presence of a relatively long alternatively spliced intron located in their first RNA recognition motif, which potentially results in an extremely truncated protein. In atRSZ33, a member of the RS2Z subfamily, this alternative splicing event was shown to be autoregulated. Here we show that atRSp31, a member of the RS subfamily, does not autoregulate alternative splicing of its similarily positioned intron. Interestingly, this alternative splicing event is regulated by atRSZ33. We demonstrate that the positions of these long introns and their capability for alternative splicing are conserved from green algae to flowering plants. Moreover, in particular alternative splicing events the splicing signals are embedded into highly conserved sequences. In different taxa, these conserved sequences occur in at least one gene within a subfamily. The evolutionary preservation of alternative splice forms together with highly conserved intron features argues for additional functions hidden in the genes of these plant-specific SR proteins.

Research paper thumbnail of Evolutionary conservation and regulation of particular alternative splicing events in plant SR proteins

Nucleic Acids Research, 2006

Alternative splicing is an important mechanism for fine tuning of gene expression at the posttran... more Alternative splicing is an important mechanism for fine tuning of gene expression at the posttranscriptional level. SR proteins govern splice site selection and spliceosome assembly. The Arabidopsis genome encodes 19 SR proteins, several of which have no orthologues in metazoan. Three of the plant specific subfamilies are characterized by the presence of a relatively long alternatively spliced intron located in their first RNA recognition motif, which potentially results in an extremely truncated protein. In atRSZ33, a member of the RS2Z subfamily, this alternative splicing event was shown to be autoregulated. Here we show that atRSp31, a member of the RS subfamily, does not autoregulate alternative splicing of its similarily positioned intron. Interestingly, this alternative splicing event is regulated by atRSZ33. We demonstrate that the positions of these long introns and their capability for alternative splicing are conserved from green algae to flowering plants. Moreover, in particular alternative splicing events the splicing signals are embedded into highly conserved sequences. In different taxa, these conserved sequences occur in at least one gene within a subfamily. The evolutionary preservation of alternative splice forms together with highly conserved intron features argues for additional functions hidden in the genes of these plant-specific SR proteins.

Research paper thumbnail of A novel strategy for obtaining kanamycin resistance in Arabidopsis thaliana by silencing an endogenous gene encoding a putative chloroplast transporter

Biotechnology Journal, 2009

The use of bacterial antibiotic resistance markers in transgenic plants raises concerns about hor... more The use of bacterial antibiotic resistance markers in transgenic plants raises concerns about horizontal gene transfer to soil bacteria. We report here that kanamycin resistance in Arabidopsis thaliana can be achieved by silencing an endogenous gene encoding a putative chloroplast transporter, which presumably imports kanamycin into chloroplasts to interfere with ribosomal RNA. Homologs of the transporter exist in other plant species, suggesting this strategy may be generally useful for selecting transformed plant cells.

Research paper thumbnail of DNA methylation variation in Arabidopsis has a genetic basis and shows evidence of local adaptation

Research paper thumbnail of DNA methylation in Arabidopsis has a genetic basis and shows evidence of local adaptation

eLife, 2015

Epigenome modulation in response to the environment potentially provides a mechanism for organism... more Epigenome modulation in response to the environment potentially provides a mechanism for organisms to adapt, both within and between generations. However, neither the extent to which this occurs, nor the molecular mechanisms involved are known. Here we investigate DNA methylation variation in Swedish Arabidopsis thaliana accessions grown at two different temperatures. Environmental effects on DNA methylation were limited to transposons, where CHH methylation was found to increase with temperature. Genomewide association mapping revealed that the extensive CHH methylation variation was strongly associated with genetic variants in both cis and trans, including a major transassociation close to the DNA methyltransferase CMT2. Unlike CHH methylation, CpG gene body methylation (GBM) on the coding region of genes was not affected by growth temperature, but was instead strongly correlated with the latitude of origin. Accessions from colder regions had higher levels of GBM for a significant fraction of the genome, and this was correlated with elevated transcription levels for the genes affected. Genome-wide association mapping revealed that this effect was largely due to trans-acting loci, a significant fraction of which showed evidence of local adaptation.

Research paper thumbnail of Temporal and tissue-specific expression of the tobacco ntf4 MAP kinase

Plant molecular biology, 2001

The large number of mitogen-activated protein (MAP) kinase genes identified to date in plants sug... more The large number of mitogen-activated protein (MAP) kinase genes identified to date in plants suggests that their encoded proteins have a wide array of functions in development and physiological responses, as has been indicated by studies on the factors which lead to the activation of these kinases. Signalling pathways involving members of a multigene family employ a variety of mechanisms to ensure response specificity, one of which is via differential gene expression. We have performed detailed analyses of the expression of the tobacco ntf4 MAP kinase gene using a variety of approaches. The ntf4 gene promoter region was isolated and a chimeric ntf4 promoter-GUS fusion construct was introduced into plants. GUS expression was detected in pollen, in developing and mature embryos, and shortly after seed germination, but not in other floral tissues and tissues such as leaf, root, or stem. This expression pattern was confirmed by northern and western analyses. In situ hybridization and i...

Research paper thumbnail of Green fluorescent protein (GFP) as a marker during pollen development

Transgenic research, 1999

The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GF... more The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GFP5ER, and GFP4S65C, under several constitutive and pollen-specific promoters throughout pollen development in Nicotiana tabacum, Arabidopsis thaliana and Antirrhinum majus is described. Immature pollen of tobacco, Arabidopsis and snapdragon, isolated at different developmental stages, were bombarded with plasmids containing the GFP and cultured in vitro for several days until maturity. The expression of GFP was monitored every day during in vitro maturation, germination and pollination, as well as after in situ pollination. The expression pattern of each GFP construct was compared in parallel experiments to that of beta-glucuronidase (GUS) constructs expressed by the same promoters. The results show that the expression level of all three GFP mutant forms was dependent on the strength of the promoter used. The strongest promoter was the DC3 promoter, and no notable differences in the inte...

Research paper thumbnail of Signal Transduction by Mitogen-activated Protein Kinases (MAPKs)

Signal Transduction by Mitogen-activated Protein Kinases (MAPKs) ERWIN HEBERLE-BORS, ORNELLA CALD... more Signal Transduction by Mitogen-activated Protein Kinases (MAPKs) ERWIN HEBERLE-BORS, ORNELLA CALDERINI, VIKTOR VORONIN, AND CATHAL ... See also Moss protonema MAP kinase activation, 65 polypeptides induced by, 66-67 Action spectra, phytochrome ...

Research paper thumbnail of Erratum to: A tobacco homolog of DCN1 is involved in pollen development and embryogenesis

Research paper thumbnail of Plant male germ line transformation

The Plant Journal, 1997

A new method to produce transgenic plants -male germ line transformation (MAGELITR) is reported. ... more A new method to produce transgenic plants -male germ line transformation (MAGELITR) is reported. Unicellular tobacco microspores were isolated from excised anthers, and DNA carrying two marker genes was transferred biolistically. The bombarded microspores were matured in vitro for 6 days, and the mature pollen was used for in vivo pollination. Seeds were recovered and putative transformants were selected on the basis of their antibiotic resistance. Five kanamycin-resistant plants were chosen for further analysis, four contained the first construct, one the second. Parallel experiments with bicellular immature pollen did not produce any transgenic plants. A detailed DNA blot and expression analysis confirmed the transgenic nature of the five plants, and a genetic analysis showed that the transgenes are transmitted to subsequent generations. MAGEMTR is a fast, regeneration-independent method, not prone to chimerism and somaclonal variation which should be genotype-independent and may be applicable in a wide range of species once in vitro maturation of pollen is established.

Research paper thumbnail of A Developmentally Regulated MAP Kinase Activated by Hydration in Tobacco Pollen

The Plant Cell, 1997

A nove1 mitogen-activated protein (MAP) kinase signaling pathway has been identified in tobacco. ... more A nove1 mitogen-activated protein (MAP) kinase signaling pathway has been identified in tobacco. This pathway is developmentally regulated during pollen maturation and is activated by hydration during pollen germination. Analysis of different stages of pollen development showed that transcriptional and translational induction of MAP kinase synthesis occurs at the mid-bicellular stage of pollen maturation. However, the MAP kinase is stored in an inactive form in the mature, dry pollen grain. Kinase activation is very rapid after hydration of the dry pollen, peaking at -5 min and decreasing thereafter. lmmunoprecipitation of the kinase activity by an anti-phosphotyrosine antibody is consistent with the activation of a MAP kinase. The kinetics of activation suggest that the MAP kinase plays a role in the activation of the pollen grain after hydration rather than in pollen tube growth.

Research paper thumbnail of MAP kinase signaling during pollen development

Sexual Plant Reproduction, 2001

... Erwin Heberle-Bors · Viktor Voronin · Alisher Touraev Pilar Sanchez Testillano · Maria Carmen... more ... Erwin Heberle-Bors · Viktor Voronin · Alisher Touraev Pilar Sanchez Testillano · Maria Carmen Risueño Cathal Wilson ... of mol-ecules involved in the cell cycle machinery, although the events of sperm cell formation and fertilization are es-sentially similar (Friedman 1999). ...

Research paper thumbnail of Methotrexate is a new selectable marker for tobacco immature pollen transformation

Plant Cell Reports, 2006

We report here a new selectable marker for tobacco immature pollen transformation based on the ex... more We report here a new selectable marker for tobacco immature pollen transformation based on the expression of dihydrofolate reductase (dhfr) gene which confers resistance to methotrexate (Mtx). Two immature pollen transformation approaches, i.e., male germ line transformation and particle bombardment of embryogenic mid-bicellular pollen have been used for the production of stable transgenic tobacco plants. In the first method, two methotrexate-resistant plants were selected from a total of 7161 seeds recovered after transformation experiments. In the second method, four methotrexate-resistant plants were obtained from 29 bombardments using 3.7×10 5 pollen grains per bombardment. Southern analysis confirmed the transgenic nature of T 0 and T 1 candidate transgenic plants, and a genetic analysis showed that the transgenes are transmitted to subsequent generations.

Research paper thumbnail of A tobacco homolog of DCN1 is involved in pollen development and embryogenesis

Plant Cell Reports, 2014

Key Message We show that DCN1 binds ubiquitin and RUB/NEDD8, associates with cullin, and is funct... more Key Message We show that DCN1 binds ubiquitin and RUB/NEDD8, associates with cullin, and is functionally conserved. DCN1 activity is required for pollen development transitions and embryogenesis, and for pollen tube growth. Abstract Plant proteomes show remarkable plasticity in reaction to environmental challenges and during developmental transitions. Some of this adaptability comes from ubiquitin-mediated protein degradation regulated by cullin-RING E3 ubiquitin ligases (CRLs). CRLs are activated through modification of the cullin subunit with the ubiquitin-like protein RUB/NEDD8 by an E3 ligase called

Research paper thumbnail of Massive genomic variation and strong selection in Arabidopsis thaliana lines from Sweden

Research paper thumbnail of The MAP kinase kinase NtMEK2 is involved in tobacco pollen germination

FEBS Letters, 2004

The tobacco ntf4 mitogen-activated protein (MAP) kinase gene (and its encoded protein p45 Ntf4 ) ... more The tobacco ntf4 mitogen-activated protein (MAP) kinase gene (and its encoded protein p45 Ntf4 ) is expressed at later stages of pollen maturation. We have found that the highly related MAP kinase SIPK is also expressed in pollen and, like p45 Ntf4 , is activated upon pollen hydration. The MAP kinase kinase NtMEK2 activates SIPK, and here we show that it can also activate p45 Ntf4 . In an attempt to inhibit the function of both MAP kinases simultaneously we constructed a loss-offunction mutant version of NtMEK2, which, in transient transformation assays, led to an inhibition of germination in the transformed pollen grains. These data indicate that NtMEK2, and by inference its substrates p45 Ntf4 and/or SIPK, are involved in pollen germination.

Research paper thumbnail of Identification of a villin-related tobacco protein as a novel cross-reactive plant allergen

FEBS Letters, 2005

In a paradigmatic approach we identified cross-reactive plant allergens for allergy diagnosis and... more In a paradigmatic approach we identified cross-reactive plant allergens for allergy diagnosis and treatment by screening of a tobacco leaf complementary DNA (cDNA) library with serum IgE from a polysensitized allergic patient. Two IgEreactive cDNA clones were isolated which code for proteins with significant sequence similarity to the actin-binding protein, villin. Northern-and Western-blotting demonstrate expression of the villin-related allergens in pollen and somatic plant tissues. In addition, villin-related proteins were detected in several plant allergen sources (tree-, grass-, weed pollen, fruits, vegetables, nuts). A recombinant C-terminal fragment of the villin-related protein was expressed in Escherichia coli, purified and shown to react specifically with allergic patients IgE. After profilin, villin-related proteins represent another family of cytoskeletal proteins, which has been identified as cross-reactive plant allergens. They may be used for the diagnosis and treatment of patients suffering from multivalent plant allergies.

Research paper thumbnail of Evolutionary conservation and regulation of particular alternative splicing events in plant SR proteins

Nucleic Acids Research, 2006

Alternative splicing is an important mechanism for fine tuning of gene expression at the posttran... more Alternative splicing is an important mechanism for fine tuning of gene expression at the posttranscriptional level. SR proteins govern splice site selection and spliceosome assembly. The Arabidopsis genome encodes 19 SR proteins, several of which have no orthologues in metazoan. Three of the plant specific subfamilies are characterized by the presence of a relatively long alternatively spliced intron located in their first RNA recognition motif, which potentially results in an extremely truncated protein. In atRSZ33, a member of the RS2Z subfamily, this alternative splicing event was shown to be autoregulated. Here we show that atRSp31, a member of the RS subfamily, does not autoregulate alternative splicing of its similarily positioned intron. Interestingly, this alternative splicing event is regulated by atRSZ33. We demonstrate that the positions of these long introns and their capability for alternative splicing are conserved from green algae to flowering plants. Moreover, in particular alternative splicing events the splicing signals are embedded into highly conserved sequences. In different taxa, these conserved sequences occur in at least one gene within a subfamily. The evolutionary preservation of alternative splice forms together with highly conserved intron features argues for additional functions hidden in the genes of these plant-specific SR proteins.

Research paper thumbnail of Evolutionary conservation and regulation of particular alternative splicing events in plant SR proteins

Nucleic Acids Research, 2006

Alternative splicing is an important mechanism for fine tuning of gene expression at the posttran... more Alternative splicing is an important mechanism for fine tuning of gene expression at the posttranscriptional level. SR proteins govern splice site selection and spliceosome assembly. The Arabidopsis genome encodes 19 SR proteins, several of which have no orthologues in metazoan. Three of the plant specific subfamilies are characterized by the presence of a relatively long alternatively spliced intron located in their first RNA recognition motif, which potentially results in an extremely truncated protein. In atRSZ33, a member of the RS2Z subfamily, this alternative splicing event was shown to be autoregulated. Here we show that atRSp31, a member of the RS subfamily, does not autoregulate alternative splicing of its similarily positioned intron. Interestingly, this alternative splicing event is regulated by atRSZ33. We demonstrate that the positions of these long introns and their capability for alternative splicing are conserved from green algae to flowering plants. Moreover, in particular alternative splicing events the splicing signals are embedded into highly conserved sequences. In different taxa, these conserved sequences occur in at least one gene within a subfamily. The evolutionary preservation of alternative splice forms together with highly conserved intron features argues for additional functions hidden in the genes of these plant-specific SR proteins.

Research paper thumbnail of A novel strategy for obtaining kanamycin resistance in Arabidopsis thaliana by silencing an endogenous gene encoding a putative chloroplast transporter

Biotechnology Journal, 2009

The use of bacterial antibiotic resistance markers in transgenic plants raises concerns about hor... more The use of bacterial antibiotic resistance markers in transgenic plants raises concerns about horizontal gene transfer to soil bacteria. We report here that kanamycin resistance in Arabidopsis thaliana can be achieved by silencing an endogenous gene encoding a putative chloroplast transporter, which presumably imports kanamycin into chloroplasts to interfere with ribosomal RNA. Homologs of the transporter exist in other plant species, suggesting this strategy may be generally useful for selecting transformed plant cells.

Research paper thumbnail of DNA methylation variation in Arabidopsis has a genetic basis and shows evidence of local adaptation

Research paper thumbnail of DNA methylation in Arabidopsis has a genetic basis and shows evidence of local adaptation

eLife, 2015

Epigenome modulation in response to the environment potentially provides a mechanism for organism... more Epigenome modulation in response to the environment potentially provides a mechanism for organisms to adapt, both within and between generations. However, neither the extent to which this occurs, nor the molecular mechanisms involved are known. Here we investigate DNA methylation variation in Swedish Arabidopsis thaliana accessions grown at two different temperatures. Environmental effects on DNA methylation were limited to transposons, where CHH methylation was found to increase with temperature. Genomewide association mapping revealed that the extensive CHH methylation variation was strongly associated with genetic variants in both cis and trans, including a major transassociation close to the DNA methyltransferase CMT2. Unlike CHH methylation, CpG gene body methylation (GBM) on the coding region of genes was not affected by growth temperature, but was instead strongly correlated with the latitude of origin. Accessions from colder regions had higher levels of GBM for a significant fraction of the genome, and this was correlated with elevated transcription levels for the genes affected. Genome-wide association mapping revealed that this effect was largely due to trans-acting loci, a significant fraction of which showed evidence of local adaptation.

Research paper thumbnail of Temporal and tissue-specific expression of the tobacco ntf4 MAP kinase

Plant molecular biology, 2001

The large number of mitogen-activated protein (MAP) kinase genes identified to date in plants sug... more The large number of mitogen-activated protein (MAP) kinase genes identified to date in plants suggests that their encoded proteins have a wide array of functions in development and physiological responses, as has been indicated by studies on the factors which lead to the activation of these kinases. Signalling pathways involving members of a multigene family employ a variety of mechanisms to ensure response specificity, one of which is via differential gene expression. We have performed detailed analyses of the expression of the tobacco ntf4 MAP kinase gene using a variety of approaches. The ntf4 gene promoter region was isolated and a chimeric ntf4 promoter-GUS fusion construct was introduced into plants. GUS expression was detected in pollen, in developing and mature embryos, and shortly after seed germination, but not in other floral tissues and tissues such as leaf, root, or stem. This expression pattern was confirmed by northern and western analyses. In situ hybridization and i...

Research paper thumbnail of Green fluorescent protein (GFP) as a marker during pollen development

Transgenic research, 1999

The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GF... more The transient expression of three mutant forms of green fluorescent protein (GFP) genes, GFP4, GFP5ER, and GFP4S65C, under several constitutive and pollen-specific promoters throughout pollen development in Nicotiana tabacum, Arabidopsis thaliana and Antirrhinum majus is described. Immature pollen of tobacco, Arabidopsis and snapdragon, isolated at different developmental stages, were bombarded with plasmids containing the GFP and cultured in vitro for several days until maturity. The expression of GFP was monitored every day during in vitro maturation, germination and pollination, as well as after in situ pollination. The expression pattern of each GFP construct was compared in parallel experiments to that of beta-glucuronidase (GUS) constructs expressed by the same promoters. The results show that the expression level of all three GFP mutant forms was dependent on the strength of the promoter used. The strongest promoter was the DC3 promoter, and no notable differences in the inte...

Research paper thumbnail of Signal Transduction by Mitogen-activated Protein Kinases (MAPKs)

Signal Transduction by Mitogen-activated Protein Kinases (MAPKs) ERWIN HEBERLE-BORS, ORNELLA CALD... more Signal Transduction by Mitogen-activated Protein Kinases (MAPKs) ERWIN HEBERLE-BORS, ORNELLA CALDERINI, VIKTOR VORONIN, AND CATHAL ... See also Moss protonema MAP kinase activation, 65 polypeptides induced by, 66-67 Action spectra, phytochrome ...

Research paper thumbnail of Erratum to: A tobacco homolog of DCN1 is involved in pollen development and embryogenesis

Research paper thumbnail of Plant male germ line transformation

The Plant Journal, 1997

A new method to produce transgenic plants -male germ line transformation (MAGELITR) is reported. ... more A new method to produce transgenic plants -male germ line transformation (MAGELITR) is reported. Unicellular tobacco microspores were isolated from excised anthers, and DNA carrying two marker genes was transferred biolistically. The bombarded microspores were matured in vitro for 6 days, and the mature pollen was used for in vivo pollination. Seeds were recovered and putative transformants were selected on the basis of their antibiotic resistance. Five kanamycin-resistant plants were chosen for further analysis, four contained the first construct, one the second. Parallel experiments with bicellular immature pollen did not produce any transgenic plants. A detailed DNA blot and expression analysis confirmed the transgenic nature of the five plants, and a genetic analysis showed that the transgenes are transmitted to subsequent generations. MAGEMTR is a fast, regeneration-independent method, not prone to chimerism and somaclonal variation which should be genotype-independent and may be applicable in a wide range of species once in vitro maturation of pollen is established.

Research paper thumbnail of A Developmentally Regulated MAP Kinase Activated by Hydration in Tobacco Pollen

The Plant Cell, 1997

A nove1 mitogen-activated protein (MAP) kinase signaling pathway has been identified in tobacco. ... more A nove1 mitogen-activated protein (MAP) kinase signaling pathway has been identified in tobacco. This pathway is developmentally regulated during pollen maturation and is activated by hydration during pollen germination. Analysis of different stages of pollen development showed that transcriptional and translational induction of MAP kinase synthesis occurs at the mid-bicellular stage of pollen maturation. However, the MAP kinase is stored in an inactive form in the mature, dry pollen grain. Kinase activation is very rapid after hydration of the dry pollen, peaking at -5 min and decreasing thereafter. lmmunoprecipitation of the kinase activity by an anti-phosphotyrosine antibody is consistent with the activation of a MAP kinase. The kinetics of activation suggest that the MAP kinase plays a role in the activation of the pollen grain after hydration rather than in pollen tube growth.

Research paper thumbnail of MAP kinase signaling during pollen development

Sexual Plant Reproduction, 2001

... Erwin Heberle-Bors · Viktor Voronin · Alisher Touraev Pilar Sanchez Testillano · Maria Carmen... more ... Erwin Heberle-Bors · Viktor Voronin · Alisher Touraev Pilar Sanchez Testillano · Maria Carmen Risueño Cathal Wilson ... of mol-ecules involved in the cell cycle machinery, although the events of sperm cell formation and fertilization are es-sentially similar (Friedman 1999). ...

Research paper thumbnail of Methotrexate is a new selectable marker for tobacco immature pollen transformation

Plant Cell Reports, 2006

We report here a new selectable marker for tobacco immature pollen transformation based on the ex... more We report here a new selectable marker for tobacco immature pollen transformation based on the expression of dihydrofolate reductase (dhfr) gene which confers resistance to methotrexate (Mtx). Two immature pollen transformation approaches, i.e., male germ line transformation and particle bombardment of embryogenic mid-bicellular pollen have been used for the production of stable transgenic tobacco plants. In the first method, two methotrexate-resistant plants were selected from a total of 7161 seeds recovered after transformation experiments. In the second method, four methotrexate-resistant plants were obtained from 29 bombardments using 3.7×10 5 pollen grains per bombardment. Southern analysis confirmed the transgenic nature of T 0 and T 1 candidate transgenic plants, and a genetic analysis showed that the transgenes are transmitted to subsequent generations.

Research paper thumbnail of A tobacco homolog of DCN1 is involved in pollen development and embryogenesis

Plant Cell Reports, 2014

Key Message We show that DCN1 binds ubiquitin and RUB/NEDD8, associates with cullin, and is funct... more Key Message We show that DCN1 binds ubiquitin and RUB/NEDD8, associates with cullin, and is functionally conserved. DCN1 activity is required for pollen development transitions and embryogenesis, and for pollen tube growth. Abstract Plant proteomes show remarkable plasticity in reaction to environmental challenges and during developmental transitions. Some of this adaptability comes from ubiquitin-mediated protein degradation regulated by cullin-RING E3 ubiquitin ligases (CRLs). CRLs are activated through modification of the cullin subunit with the ubiquitin-like protein RUB/NEDD8 by an E3 ligase called

Research paper thumbnail of Massive genomic variation and strong selection in Arabidopsis thaliana lines from Sweden

Research paper thumbnail of The MAP kinase kinase NtMEK2 is involved in tobacco pollen germination

FEBS Letters, 2004

The tobacco ntf4 mitogen-activated protein (MAP) kinase gene (and its encoded protein p45 Ntf4 ) ... more The tobacco ntf4 mitogen-activated protein (MAP) kinase gene (and its encoded protein p45 Ntf4 ) is expressed at later stages of pollen maturation. We have found that the highly related MAP kinase SIPK is also expressed in pollen and, like p45 Ntf4 , is activated upon pollen hydration. The MAP kinase kinase NtMEK2 activates SIPK, and here we show that it can also activate p45 Ntf4 . In an attempt to inhibit the function of both MAP kinases simultaneously we constructed a loss-offunction mutant version of NtMEK2, which, in transient transformation assays, led to an inhibition of germination in the transformed pollen grains. These data indicate that NtMEK2, and by inference its substrates p45 Ntf4 and/or SIPK, are involved in pollen germination.

Research paper thumbnail of Identification of a villin-related tobacco protein as a novel cross-reactive plant allergen

FEBS Letters, 2005

In a paradigmatic approach we identified cross-reactive plant allergens for allergy diagnosis and... more In a paradigmatic approach we identified cross-reactive plant allergens for allergy diagnosis and treatment by screening of a tobacco leaf complementary DNA (cDNA) library with serum IgE from a polysensitized allergic patient. Two IgEreactive cDNA clones were isolated which code for proteins with significant sequence similarity to the actin-binding protein, villin. Northern-and Western-blotting demonstrate expression of the villin-related allergens in pollen and somatic plant tissues. In addition, villin-related proteins were detected in several plant allergen sources (tree-, grass-, weed pollen, fruits, vegetables, nuts). A recombinant C-terminal fragment of the villin-related protein was expressed in Escherichia coli, purified and shown to react specifically with allergic patients IgE. After profilin, villin-related proteins represent another family of cytoskeletal proteins, which has been identified as cross-reactive plant allergens. They may be used for the diagnosis and treatment of patients suffering from multivalent plant allergies.