The Experts below are selected from a list of 519 Experts worldwide ranked by ideXlab platform
Vicente Conejero - One of the best experts on this subject based on the ideXlab platform.
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cDNA Cloning of Viroid-Induced Tomato Pathogenesis-Related Protein P23 (Characterization as a Vacuolar Antifungal Factor)
Plant physiology, 1993Co-Authors: Ismael Rodrigo, Pablo Vera, Pablo Tornero, Jose Hernandez-yago, Vicente ConejeroAbstract:A 23-kD pathogenesis-related Protein (P23) is induced in tomato (Lycopersicon esculentum Mill, cv Rutgers) plants when infected with citrus exocortis viroid. This Protein is homologous to the salt-induced tomato NP24 Protein (I. Rodrigo, P. Vera, R. Frank, V. Conejero [1991] Plant Mol Biol 16: 931–)934). Further characterization of P23 has shown that this Protein accumulates in vacuoles in association with dense inclusion bodies. In vitro assays indicated that the purified P23 Protein inhibits the growth of several phytopathogenic fungi. P23-coding cDNA clones were isolated from viroid-induced and ethylene-induced libraries. Southern analysis showed that at least two genes could encode P23 or P23-related products. The accumulation of P23 Protein correlated with the accumulation of its mRNA. Sequence analysis revealed significant differences in both coding and downstream untranslated regions between the cDNA sequences corresponding to the viroid-induced P23 and the salt stress-induced NP24 Proteins.
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cDNA Cloning of Viroid-lnduced Tomato Pathogenesis-Related Protein P23'
1993Co-Authors: Pablo Vera, Pablo Tornero, Jose Hernandez-yago, Vicente Conejero, Amadeo De SaboyaAbstract:A 23-kD pathogenesis-related Protein (P23) is induced in tomato (Lycopersicon esculentum Mill, cv Rutgers) plants when infeded with citrus exocortis viroid. This Protein is homologous to the saltinduced tomato NP24 Protein (I. Rodrigo, P. Vera, R. Frank, V. Conejero [1991] Plant MOI Biol 16 931-934). Further characterization of P23 has shown that this Protein accumulates in vacuoles in association with dense inclusion bodies. In vitro assays indicated that the purified P23 Protein inhibits the growth of several phytopathogenic fungi. P23-coding cDNA clones were isolated from viroid-induced and ethylene-induced libraries. Southern analysis showed that at least two genes could encode P23 or P23-related products. The accumulation of P23 Protein correlated with the accumulation of its mRNA. Sequence analysis revealed significant differences in both coding and downstream untranslated regions between the cDNA sequences corresponding to the viroid-induced P23 and the salt stress-induced NP24 Proteins.
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Identification of the viroid-induced tomato pathogenesis-related (PR) Protein P23 as the thaumatin-like tomato Protein NP24 associated with osmotic stress.
Plant molecular biology, 1991Co-Authors: Ismael Rodrigo, Pablo Vera, Rainer Frank, Vicente ConejeroAbstract:P23, a 23 kDa pathogenesis-related (PR) Protein, was purified from citrus exocortis viroid (CEVd)-infected tomato leaves. Partial amino acid sequencing of this Protein including the N-terminal and nine additional tryptic fragments covering about 50% of its primary structure revealed extensive homologies to the members of the family of plant thaumatin-like Proteins. Sequence alignment revealed that tomato P23 is the previously described NP24 Protein found to be associated to osmotic stress in tomato. In view of this fact the possible role of pathogenesis-related P23 Protein as a component of a general mechanism of response of the plant is discussed.
Ismael Rodrigo - One of the best experts on this subject based on the ideXlab platform.
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cDNA Cloning of Viroid-Induced Tomato Pathogenesis-Related Protein P23 (Characterization as a Vacuolar Antifungal Factor)
Plant physiology, 1993Co-Authors: Ismael Rodrigo, Pablo Vera, Pablo Tornero, Jose Hernandez-yago, Vicente ConejeroAbstract:A 23-kD pathogenesis-related Protein (P23) is induced in tomato (Lycopersicon esculentum Mill, cv Rutgers) plants when infected with citrus exocortis viroid. This Protein is homologous to the salt-induced tomato NP24 Protein (I. Rodrigo, P. Vera, R. Frank, V. Conejero [1991] Plant Mol Biol 16: 931–)934). Further characterization of P23 has shown that this Protein accumulates in vacuoles in association with dense inclusion bodies. In vitro assays indicated that the purified P23 Protein inhibits the growth of several phytopathogenic fungi. P23-coding cDNA clones were isolated from viroid-induced and ethylene-induced libraries. Southern analysis showed that at least two genes could encode P23 or P23-related products. The accumulation of P23 Protein correlated with the accumulation of its mRNA. Sequence analysis revealed significant differences in both coding and downstream untranslated regions between the cDNA sequences corresponding to the viroid-induced P23 and the salt stress-induced NP24 Proteins.
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Identification of the viroid-induced tomato pathogenesis-related (PR) Protein P23 as the thaumatin-like tomato Protein NP24 associated with osmotic stress.
Plant molecular biology, 1991Co-Authors: Ismael Rodrigo, Pablo Vera, Rainer Frank, Vicente ConejeroAbstract:P23, a 23 kDa pathogenesis-related (PR) Protein, was purified from citrus exocortis viroid (CEVd)-infected tomato leaves. Partial amino acid sequencing of this Protein including the N-terminal and nine additional tryptic fragments covering about 50% of its primary structure revealed extensive homologies to the members of the family of plant thaumatin-like Proteins. Sequence alignment revealed that tomato P23 is the previously described NP24 Protein found to be associated to osmotic stress in tomato. In view of this fact the possible role of pathogenesis-related P23 Protein as a component of a general mechanism of response of the plant is discussed.
Leandro Peña - One of the best experts on this subject based on the ideXlab platform.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23
Plant Molecular Biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Pedro Julián Flores Moreno, Leandro Peña, Ricardo FloresAbstract:Key message Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23.
Plant molecular biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Leandro Peña, Pedro Moreno, Ricardo FloresAbstract:Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle. The genome of citrus tristeza virus (CTV), genus Closterovirus family Closteroviridae, is a single-stranded (+) RNA potentially encoding at least 17 Proteins. One (P23), an RNA-binding Protein of 209 amino acids with a putative Zn-finger and some basic motifs, displays singular features: (i) it has no homologues in other closteroviruses, (ii) it accumulates mainly in the nucleolus and Cajal bodies, and in plasmodesmata, and (iii) it mediates asymmetric accumulation of CTV RNA strands, intracellular suppression of RNA silencing, induction of some CTV syndromes and enhancement of systemic infection when expressed as a transgene ectopically or in phloem-associated cells in several Citrus spp. Here, a yeast two-hybrid screening of an expression library of Nicotiana benthamiana (a symptomatic experimental host for CTV), identified a transducin/WD40 domain Protein and the cytosolic glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as potential host interactors with P23. Bimolecular fluorescence complementation corroborated the P23-GAPDH interaction in planta and showed that P23 interacts with itself in the nucleolus, Cajal bodies and plasmodesmata, and with GAPDH in the cytoplasm (forming aggregates) and in plasmodesmata. The latter interaction was preserved in a P23 deletion mutant affecting the C-terminal domain, but not in two others affecting the Zn-finger and one internal basic motif. Virus-induced gene silencing of GAPDH mRNA resulted in a decrease of CTV titer as revealed by real-time RT-quantitative PCR and RNA gel-blot hybridization. Thus, like other viruses, CTV seems to co-opt GAPDH, via interaction with P23, to facilitate its infectious cycle.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23
Plant Molecular Biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Leandro Peña, Pedro Moreno, Ricardo FloresAbstract:Key message Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle. Abstract The genome of citrus tristeza virus (CTV), genus Closterovirus family Closteroviridae , is a single-stranded (+) RNA potentially encoding at least 17 Proteins. One (P23), an RNA-binding Protein of 209 amino acids with a putative Zn-finger and some basic motifs, displays singular features: (i) it has no homologues in other closteroviruses, (ii) it accumulates mainly in the nucleolus and Cajal bodies, and in plasmodesmata, and (iii) it mediates asymmetric accumulation of CTV RNA strands, intracellular suppression of RNA silencing, induction of some CTV syndromes and enhancement of systemic infection when expressed as a transgene ectopically or in phloem-associated cells in several Citrus spp. Here, a yeast two-hybrid screening of an expression library of Nicotiana benthamiana (a symptomatic experimental host for CTV), identified a transducin/WD40 domain Protein and the cytosolic glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as potential host interactors with P23. Bimolecular fluorescence complementation corroborated the P23-GAPDH interaction in planta and showed that P23 interacts with itself in the nucleolus, Cajal bodies and plasmodesmata, and with GAPDH in the cytoplasm (forming aggregates) and in plasmodesmata. The latter interaction was preserved in a P23 deletion mutant affecting the C-terminal domain, but not in two others affecting the Zn-finger and one internal basic motif. Virus-induced gene silencing of GAPDH mRNA resulted in a decrease of CTV titer as revealed by real-time RT-quantitative PCR and RNA gel-blot hybridization. Thus, like other viruses, CTV seems to co-opt GAPDH, via interaction with P23, to facilitate its infectious cycle.
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Symptoms induced by transgenic expression of P23 from Citrus tristeza virus in phloem-associated cells of Mexican lime mimic virus infection without the aberrations accompanying constitutive expression
Molecular plant pathology, 2014Co-Authors: Nuria Soler, Luis Navarro, Ricardo Flores, Pedro Moreno, Carmelo López, Carmen Fagoaga, Leandro PeñaAbstract:Summary Citrus tristeza virus (CTV) is phloem restricted in natural citrus hosts. The 23-kDa Protein (P23) encoded by the virus is an RNA silencing suppressor and a pathogenicity determinant. The expression of P23, or its N-terminal 157-amino-acid fragment comprising the zinc finger and flanking basic motifs, driven by the constitutive 35S promoter of cauliflower mosaic virus, induces CTV-like symptoms and other aberrations in transgenic citrus. To better define the role of P23 in CTV pathogenesis, we compared the phenotypes of Mexican lime transformed with P23-derived transgenes from the severe T36 and mild T317 CTV isolates under the control of the phloem-specific promoter from Commelina yellow mottle virus (CoYMV) or the 35S promoter. Expression of the constructs restricted to the phloem induced a phenotype resembling CTV-specific symptoms (vein clearing and necrosis, and stem pitting), but not the non-specific aberrations (such as mature leaf epinasty and yellow pinpoints, growth cessation and apical necrosis) observed when P23 was ectopically expressed. Furthermore, vein necrosis and stem pitting in Mexican lime appeared to be specifically associated with P23 from T36. Phloem-specific accumulation of the P23Δ158–209(T36) fragment was sufficient to induce the same anomalies, indicating that the region comprising the N-terminal 157 amino acids of P23 is responsible (at least in part) for the vein clearing, stem pitting and, possibly, vein corking in this host.
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Transgenic citrus plants expressing the citrus tristeza virus P23 Protein exhibit viral-like symptoms.
Molecular plant pathology, 2001Co-Authors: Riadh Ghorbel, Ricardo Flores, Pedro Moreno, Carmelo López, Carmen Fagoaga, Luis Rey Navarro, Leandro PeñaAbstract:Summary The 23 kDa Protein (P23) coded by the 3′-terminal gene of Citrus tristeza virus (CTV), a member of the genus Closterovirus with the largest genome among plant RNA viruses, is an RNA-binding Protein that contains a motif rich in cysteine and histidine residues in the core of a putative zinc-finger domain. On this basis, a regulatory role for CTV replication or gene expression has been suggested for P23. To explore whether over-expression of this Protein in transgenic plants could affect the normal CTV infection process, transgenic Mexican lime plants were generated carrying the P23 transgene, or a truncated version thereof, under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Constitutive expression of P23 induced phenotypic aberrations that resembled symptoms incited by CTV in non-transgenic lime plants, whereas transgenic plants expressing the P23 truncated version were normal. The onset of CTV-like symptoms in P23-transgenic plants was associated with the expression of P23, and its accumulation level paralleled the intensity of the symptoms. This demonstrates that P23 is involved in symptom development and that it most likely plays a key role in CTV pathogenesis. This is the first case in which a Protein encoded by a woody plant-infecting RNA virus has been identified as being directly involved in pathogenesis in its natural host. This finding also delimits a small region of the large CTV genome for the future mapping of specific pathogenic determinants.
Ricardo Flores - One of the best experts on this subject based on the ideXlab platform.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23
Plant Molecular Biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Pedro Julián Flores Moreno, Leandro Peña, Ricardo FloresAbstract:Key message Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23.
Plant molecular biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Leandro Peña, Pedro Moreno, Ricardo FloresAbstract:Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle. The genome of citrus tristeza virus (CTV), genus Closterovirus family Closteroviridae, is a single-stranded (+) RNA potentially encoding at least 17 Proteins. One (P23), an RNA-binding Protein of 209 amino acids with a putative Zn-finger and some basic motifs, displays singular features: (i) it has no homologues in other closteroviruses, (ii) it accumulates mainly in the nucleolus and Cajal bodies, and in plasmodesmata, and (iii) it mediates asymmetric accumulation of CTV RNA strands, intracellular suppression of RNA silencing, induction of some CTV syndromes and enhancement of systemic infection when expressed as a transgene ectopically or in phloem-associated cells in several Citrus spp. Here, a yeast two-hybrid screening of an expression library of Nicotiana benthamiana (a symptomatic experimental host for CTV), identified a transducin/WD40 domain Protein and the cytosolic glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as potential host interactors with P23. Bimolecular fluorescence complementation corroborated the P23-GAPDH interaction in planta and showed that P23 interacts with itself in the nucleolus, Cajal bodies and plasmodesmata, and with GAPDH in the cytoplasm (forming aggregates) and in plasmodesmata. The latter interaction was preserved in a P23 deletion mutant affecting the C-terminal domain, but not in two others affecting the Zn-finger and one internal basic motif. Virus-induced gene silencing of GAPDH mRNA resulted in a decrease of CTV titer as revealed by real-time RT-quantitative PCR and RNA gel-blot hybridization. Thus, like other viruses, CTV seems to co-opt GAPDH, via interaction with P23, to facilitate its infectious cycle.
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Citrus tristeza virus co-opts glyceraldehyde 3-phosphate dehydrogenase for its infectious cycle by interacting with the viral-encoded Protein P23
Plant Molecular Biology, 2018Co-Authors: Susana Ruiz-ruiz, Roberta Spanò, Luis Navarro, Leandro Peña, Pedro Moreno, Ricardo FloresAbstract:Key message Citrus tristeza virus encodes a unique Protein, P23, with multiple functional roles that include co-option of the cytoplasmic glyceraldehyde 3-phosphate dehydrogenase to facilitate the viral infectious cycle. Abstract The genome of citrus tristeza virus (CTV), genus Closterovirus family Closteroviridae , is a single-stranded (+) RNA potentially encoding at least 17 Proteins. One (P23), an RNA-binding Protein of 209 amino acids with a putative Zn-finger and some basic motifs, displays singular features: (i) it has no homologues in other closteroviruses, (ii) it accumulates mainly in the nucleolus and Cajal bodies, and in plasmodesmata, and (iii) it mediates asymmetric accumulation of CTV RNA strands, intracellular suppression of RNA silencing, induction of some CTV syndromes and enhancement of systemic infection when expressed as a transgene ectopically or in phloem-associated cells in several Citrus spp. Here, a yeast two-hybrid screening of an expression library of Nicotiana benthamiana (a symptomatic experimental host for CTV), identified a transducin/WD40 domain Protein and the cytosolic glyceraldehyde 3-phosphate dehydrogenase (GAPDH) as potential host interactors with P23. Bimolecular fluorescence complementation corroborated the P23-GAPDH interaction in planta and showed that P23 interacts with itself in the nucleolus, Cajal bodies and plasmodesmata, and with GAPDH in the cytoplasm (forming aggregates) and in plasmodesmata. The latter interaction was preserved in a P23 deletion mutant affecting the C-terminal domain, but not in two others affecting the Zn-finger and one internal basic motif. Virus-induced gene silencing of GAPDH mRNA resulted in a decrease of CTV titer as revealed by real-time RT-quantitative PCR and RNA gel-blot hybridization. Thus, like other viruses, CTV seems to co-opt GAPDH, via interaction with P23, to facilitate its infectious cycle.
-
Symptoms induced by transgenic expression of P23 from Citrus tristeza virus in phloem-associated cells of Mexican lime mimic virus infection without the aberrations accompanying constitutive expression
Molecular plant pathology, 2014Co-Authors: Nuria Soler, Luis Navarro, Ricardo Flores, Pedro Moreno, Carmelo López, Carmen Fagoaga, Leandro PeñaAbstract:Summary Citrus tristeza virus (CTV) is phloem restricted in natural citrus hosts. The 23-kDa Protein (P23) encoded by the virus is an RNA silencing suppressor and a pathogenicity determinant. The expression of P23, or its N-terminal 157-amino-acid fragment comprising the zinc finger and flanking basic motifs, driven by the constitutive 35S promoter of cauliflower mosaic virus, induces CTV-like symptoms and other aberrations in transgenic citrus. To better define the role of P23 in CTV pathogenesis, we compared the phenotypes of Mexican lime transformed with P23-derived transgenes from the severe T36 and mild T317 CTV isolates under the control of the phloem-specific promoter from Commelina yellow mottle virus (CoYMV) or the 35S promoter. Expression of the constructs restricted to the phloem induced a phenotype resembling CTV-specific symptoms (vein clearing and necrosis, and stem pitting), but not the non-specific aberrations (such as mature leaf epinasty and yellow pinpoints, growth cessation and apical necrosis) observed when P23 was ectopically expressed. Furthermore, vein necrosis and stem pitting in Mexican lime appeared to be specifically associated with P23 from T36. Phloem-specific accumulation of the P23Δ158–209(T36) fragment was sufficient to induce the same anomalies, indicating that the region comprising the N-terminal 157 amino acids of P23 is responsible (at least in part) for the vein clearing, stem pitting and, possibly, vein corking in this host.
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Transgenic citrus plants expressing the citrus tristeza virus P23 Protein exhibit viral-like symptoms.
Molecular plant pathology, 2001Co-Authors: Riadh Ghorbel, Ricardo Flores, Pedro Moreno, Carmelo López, Carmen Fagoaga, Luis Rey Navarro, Leandro PeñaAbstract:Summary The 23 kDa Protein (P23) coded by the 3′-terminal gene of Citrus tristeza virus (CTV), a member of the genus Closterovirus with the largest genome among plant RNA viruses, is an RNA-binding Protein that contains a motif rich in cysteine and histidine residues in the core of a putative zinc-finger domain. On this basis, a regulatory role for CTV replication or gene expression has been suggested for P23. To explore whether over-expression of this Protein in transgenic plants could affect the normal CTV infection process, transgenic Mexican lime plants were generated carrying the P23 transgene, or a truncated version thereof, under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Constitutive expression of P23 induced phenotypic aberrations that resembled symptoms incited by CTV in non-transgenic lime plants, whereas transgenic plants expressing the P23 truncated version were normal. The onset of CTV-like symptoms in P23-transgenic plants was associated with the expression of P23, and its accumulation level paralleled the intensity of the symptoms. This demonstrates that P23 is involved in symptom development and that it most likely plays a key role in CTV pathogenesis. This is the first case in which a Protein encoded by a woody plant-infecting RNA virus has been identified as being directly involved in pathogenesis in its natural host. This finding also delimits a small region of the large CTV genome for the future mapping of specific pathogenic determinants.
Pablo Vera - One of the best experts on this subject based on the ideXlab platform.
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cDNA Cloning of Viroid-Induced Tomato Pathogenesis-Related Protein P23 (Characterization as a Vacuolar Antifungal Factor)
Plant physiology, 1993Co-Authors: Ismael Rodrigo, Pablo Vera, Pablo Tornero, Jose Hernandez-yago, Vicente ConejeroAbstract:A 23-kD pathogenesis-related Protein (P23) is induced in tomato (Lycopersicon esculentum Mill, cv Rutgers) plants when infected with citrus exocortis viroid. This Protein is homologous to the salt-induced tomato NP24 Protein (I. Rodrigo, P. Vera, R. Frank, V. Conejero [1991] Plant Mol Biol 16: 931–)934). Further characterization of P23 has shown that this Protein accumulates in vacuoles in association with dense inclusion bodies. In vitro assays indicated that the purified P23 Protein inhibits the growth of several phytopathogenic fungi. P23-coding cDNA clones were isolated from viroid-induced and ethylene-induced libraries. Southern analysis showed that at least two genes could encode P23 or P23-related products. The accumulation of P23 Protein correlated with the accumulation of its mRNA. Sequence analysis revealed significant differences in both coding and downstream untranslated regions between the cDNA sequences corresponding to the viroid-induced P23 and the salt stress-induced NP24 Proteins.
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cDNA Cloning of Viroid-lnduced Tomato Pathogenesis-Related Protein P23'
1993Co-Authors: Pablo Vera, Pablo Tornero, Jose Hernandez-yago, Vicente Conejero, Amadeo De SaboyaAbstract:A 23-kD pathogenesis-related Protein (P23) is induced in tomato (Lycopersicon esculentum Mill, cv Rutgers) plants when infeded with citrus exocortis viroid. This Protein is homologous to the saltinduced tomato NP24 Protein (I. Rodrigo, P. Vera, R. Frank, V. Conejero [1991] Plant MOI Biol 16 931-934). Further characterization of P23 has shown that this Protein accumulates in vacuoles in association with dense inclusion bodies. In vitro assays indicated that the purified P23 Protein inhibits the growth of several phytopathogenic fungi. P23-coding cDNA clones were isolated from viroid-induced and ethylene-induced libraries. Southern analysis showed that at least two genes could encode P23 or P23-related products. The accumulation of P23 Protein correlated with the accumulation of its mRNA. Sequence analysis revealed significant differences in both coding and downstream untranslated regions between the cDNA sequences corresponding to the viroid-induced P23 and the salt stress-induced NP24 Proteins.
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Identification of the viroid-induced tomato pathogenesis-related (PR) Protein P23 as the thaumatin-like tomato Protein NP24 associated with osmotic stress.
Plant molecular biology, 1991Co-Authors: Ismael Rodrigo, Pablo Vera, Rainer Frank, Vicente ConejeroAbstract:P23, a 23 kDa pathogenesis-related (PR) Protein, was purified from citrus exocortis viroid (CEVd)-infected tomato leaves. Partial amino acid sequencing of this Protein including the N-terminal and nine additional tryptic fragments covering about 50% of its primary structure revealed extensive homologies to the members of the family of plant thaumatin-like Proteins. Sequence alignment revealed that tomato P23 is the previously described NP24 Protein found to be associated to osmotic stress in tomato. In view of this fact the possible role of pathogenesis-related P23 Protein as a component of a general mechanism of response of the plant is discussed.
