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George Bruening - One of the best experts on this subject based on the ideXlab platform.
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formation of circular satellite Tobacco Ringspot Virus rna in protoplasts transiently expressing the linear rna
Virology, 1997Co-Authors: Catherine Chay, Xia Guan, George BrueningAbstract:The most abundant form of the satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) is a linear, unit length molecule of 359 nucleotide residues, designated L−(+)M. A postulated replication scheme for the satellite RNA has as its first, and apparently Virus-independent, step the ligation of L−(+)M into the corresponding circular form C−(+)M. We transiently expressed L−(+)M wild type and L−(+)M mutants in Tobacco protoplasts using an African cassava mosaic geminiVirus vector. Measured extents of C−(+)M accumulation were correlated with computer-predicted folding to suggest wild-type secondary structure elements that might be deleted without reducing ligation. A 127-nucleotide residue mutant L−(+)M was created by replacing, with 7 and 3 residues, respectively, nucleotide residues 53–211 and 268–350, each of which was predicted to form a set of three adjacent imperfect stem-loops in wild-type L−(+)M. The mutant L−(+)M was found to be extensively ligated to C−(+)M in protoplasts and to retain a calculated helix of the wild-type molecule that incorporates the 3′ terminal sequence. A trinucleotide in the 3′ region was mutated so as to disrupt and restore, respectively, the calculated helix, reducing and restoring, respectively, C−(+)M formation. These results suggest that the 3′ stem contributes to the suitability of the small L−(+)M molecules as a substrate for a protoplast RNA ligase and that computed folding of sTRSV RNA may be predictive of sTRSV RNA structurein vivo.
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trace amount of satellite rna associated with Tobacco Ringspot Virus increase stimulated by nonaccumulating satellite rna mutants
Virology, 1995Co-Authors: B K Passmore, Hans Van Tol, Jamal M. Buzayan, D Stabinsky, George BrueningAbstract:The small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) is dependent on Tobacco Ringspot Virus (TRSV) for replication and encapsidation. sTRSV RNA has appeared during serial passage of certain TRSV strains in some hosts. Co-inoculation of bean with TRSV and either of two related, nonaccumulating mutants of sTRSV RNA induced the appearance of sTRSV RNA in a single passage (van Tol et al., 1991, Virology 180, 23-30). The sTRSV RNA obtained after serial passage and after co-inoculation have the same nucleotide sequence, designated the endogenous sequence. The endogenous sTRSV RNA nucleotide sequence differs from that of each of the nonaccumulating sTRSV RNA at three positions. In order to detect possible trace amounts of endogenous satellite RNA in virion RNA preparations, RNA from two TRSV isolates was subjected to reverse transcription and polymerase chain reaction of the transcript (RT-PCR), using primers with sTRSV RNA terminal sequences. The yield of RT-PCR product suggests that the virion RNA preparations contained approximately 0.1 fg of sTRSV RNA per microgram of virion RNA. The nucleotide sequence of the RT-PCR product corresponded to that of the endogenous sTRSV RNA. The endogenous sTRSV RNA of TRSV inocula appears to be latent, being maintained in very small amounts during serial passage of TRSV in some hosts but capable of dramatic increase during serial passage in other hosts or when TRSV was co-inoculated with either of two specific sTRSV RNA mutants. Ten other nonaccumulating sTRSV RNA mutants did not induce a detected increase in sTRSV RNA.
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increase of satellite Tobacco Ringspot Virus rna initiated by inoculating circular rna
Virology, 1995Co-Authors: Jamal M. Buzayan, Hans Van Tol, Pierre Zalloua, George BrueningAbstract:Abstract A small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) generates circular and linear molecules of unit length and repetitive sequence, linear multimers during replication. The phosphodiester junction joining the unit satellite RNA sequences in multimeric and circular RNA resisted base-catalyzed cleavage in circles but not in linear dimers. We postulate that junctions of multimeric satellite RNA form during synthesis of the polyribonucleotide chain, whereas those of circular RNA result from a ligation reaction that introduces a group blocking the junction 2′-hydroxyl. To test the relative effectiveness of linear and circular satellite RNAs in initiating replication, we inoculated onto bean ( Phaseolus vulgaris cv Black Valentine) the four possible pairs of satellite RNA molecules, one member of each pair having the wild-type sTRSV RNA sequence and the other that of the replicating mutant 51AG/212CU, with each sequence provided as the unit circular or linear form. The relative amounts of wild-type and mutant satellite RNA sequence recovered from progeny virions reflected their relative abundances in the inoculum without regard to whether the sequence was supplied as a linear or a circular molecule. These results are consistent with models for the replication of the satellite RNA in which a circular form of the satellite RNA is a template for rolling circle transcription or is otherwise a replication intermediate or is readily converted to an intermediate. We also show that a circular form of a nonaccumulating satellite RNA mutant induced an increase in a satellite RNA that is endogenous to some Tobacco Ringspot Virus virion preparations, as demonstrated previously for the linear form.
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similar structure and reactivity of satellite Tobacco Ringspot Virus rna obtained from infected tissue and by in vitro transcription
Virology, 1993Co-Authors: B K Passmore, George BrueningAbstract:The 359 nucleotide residue (nt) satellite RNA of Tobacco Ringspot Virus increases detectably only in association with replicating Tobacco Ringspot Virus and becomes encapsidated in the Virus coat protein. Results from previous reports are consistent with participation of rolling circle transcription in replication of the satellite RNA: (i) both the more abundant plus polarity satellite RNA, s(+)RNA and the complementary s(-)RNA occur in multimeric forms that self-cleave to release the unit length, 359 nt satellite RNA, (ii) circles of both s(+)RNA and s(-)RNA are present in extracts of infected tissue, and (iii) s(-)RNA, but not s(+)RNA, spontaneously and efficiently circularizes in vitro. Our analyses of RNA in tissue extracts suggest that s(+)RNA of all forms is about 100-fold more abundant than s(-)RNA. Nucleic acids were purified rapidly to minimize interconversion of linear and circular forms. For s(+)RNA and for s(-)RNA, the circular and the linear forms were detected in about equal amounts in tissue extracts. The linear s(-)RNA from tissue extracts was found to have the same 5'-terminal sequence as previously was found for s(-)RNA self-cleaved from in vitro transcripts. Like s(-)RNA synthesized in vitro, the circular and linear s(-)RNA from tissue extracts spontaneously and readily interconverted during incubation in vitro. In contrast, the bulk of the circular and linear forms of s(+)RNA were stable. The very limited interconversion of s(+)RNA forms in vitro suggests that circulation in vivo is enzymically catalyzed. Encapsidated satellite RNA was found to be composed of linear, unit length and multimeric forms, including previously undocumented s(-)RNA present in approximately the same relative abundance compared to s(+)RNA as was observed for RNA from tissue extracts. Circles were not detected in encapsidated RNA. We interpret our results in the context of a rolling circle model for satellite RNA replication.
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evolution and replication of Tobacco Ringspot Virus satellite rna mutants
The EMBO Journal, 1993Co-Authors: C Robaglia, George Bruening, Jim Haseloff, Wayne L GerlachAbstract:The replication properties of linker insertion-deletion mutants of Tobacco Ringspot Virus satellite RNA have been studied by amplification in plants infected with the helper Virus. Sequence analysis of the cDNAs corresponding to the replicated forms shows that only one of the original mutated molecules replicates unaltered, and in general new variants accumulate. Depending on the location of the original mutation three types of sequence modifications were observed: (i) deletion of the mutated region followed by sequence duplication, (ii) sequence duplication and deletion outside of the mutated region and (iii) limited rearrangements at the site of mutation. The mutant that replicates without sequence changes accumulates linear multimeric forms suggesting that self-cleavage is affected although the sequence alteration does not involve the hammerhead catalytic domain. Alternative RNA conformations are likely to play a role in the origin of this phenotype and in the formation of sequence duplications. These results demonstrate the great structural flexibility of this satellite RNA.
Jamal M. Buzayan - One of the best experts on this subject based on the ideXlab platform.
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trace amount of satellite rna associated with Tobacco Ringspot Virus increase stimulated by nonaccumulating satellite rna mutants
Virology, 1995Co-Authors: B K Passmore, Hans Van Tol, Jamal M. Buzayan, D Stabinsky, George BrueningAbstract:The small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) is dependent on Tobacco Ringspot Virus (TRSV) for replication and encapsidation. sTRSV RNA has appeared during serial passage of certain TRSV strains in some hosts. Co-inoculation of bean with TRSV and either of two related, nonaccumulating mutants of sTRSV RNA induced the appearance of sTRSV RNA in a single passage (van Tol et al., 1991, Virology 180, 23-30). The sTRSV RNA obtained after serial passage and after co-inoculation have the same nucleotide sequence, designated the endogenous sequence. The endogenous sTRSV RNA nucleotide sequence differs from that of each of the nonaccumulating sTRSV RNA at three positions. In order to detect possible trace amounts of endogenous satellite RNA in virion RNA preparations, RNA from two TRSV isolates was subjected to reverse transcription and polymerase chain reaction of the transcript (RT-PCR), using primers with sTRSV RNA terminal sequences. The yield of RT-PCR product suggests that the virion RNA preparations contained approximately 0.1 fg of sTRSV RNA per microgram of virion RNA. The nucleotide sequence of the RT-PCR product corresponded to that of the endogenous sTRSV RNA. The endogenous sTRSV RNA of TRSV inocula appears to be latent, being maintained in very small amounts during serial passage of TRSV in some hosts but capable of dramatic increase during serial passage in other hosts or when TRSV was co-inoculated with either of two specific sTRSV RNA mutants. Ten other nonaccumulating sTRSV RNA mutants did not induce a detected increase in sTRSV RNA.
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increase of satellite Tobacco Ringspot Virus rna initiated by inoculating circular rna
Virology, 1995Co-Authors: Jamal M. Buzayan, Hans Van Tol, Pierre Zalloua, George BrueningAbstract:Abstract A small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) generates circular and linear molecules of unit length and repetitive sequence, linear multimers during replication. The phosphodiester junction joining the unit satellite RNA sequences in multimeric and circular RNA resisted base-catalyzed cleavage in circles but not in linear dimers. We postulate that junctions of multimeric satellite RNA form during synthesis of the polyribonucleotide chain, whereas those of circular RNA result from a ligation reaction that introduces a group blocking the junction 2′-hydroxyl. To test the relative effectiveness of linear and circular satellite RNAs in initiating replication, we inoculated onto bean ( Phaseolus vulgaris cv Black Valentine) the four possible pairs of satellite RNA molecules, one member of each pair having the wild-type sTRSV RNA sequence and the other that of the replicating mutant 51AG/212CU, with each sequence provided as the unit circular or linear form. The relative amounts of wild-type and mutant satellite RNA sequence recovered from progeny virions reflected their relative abundances in the inoculum without regard to whether the sequence was supplied as a linear or a circular molecule. These results are consistent with models for the replication of the satellite RNA in which a circular form of the satellite RNA is a template for rolling circle transcription or is otherwise a replication intermediate or is readily converted to an intermediate. We also show that a circular form of a nonaccumulating satellite RNA mutant induced an increase in a satellite RNA that is endogenous to some Tobacco Ringspot Virus virion preparations, as demonstrated previously for the linear form.
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evidence for spontaneous circle formation in the replication of the satellite rna of Tobacco Ringspot Virus
Virology, 1991Co-Authors: Hans Van Tol, Jamal M. Buzayan, George BrueningAbstract:Abstract Replication of the satellite RNA of Tobacco Ringspot Virus (sTobRV RNA) has been postulated to require rolling circle transcription. The expected product of rolling circle transcription, multimeric sTobRV RNA, is known to undergo self-cleavage in vitro to release unit-length sTobRV RNA. A spontaneous, efficient, not enzymically-catalyzed in vitro circularization reaction is characteristic of unit-length sTobRV RNA of the less abundant, (−) polarity. We mutated sTobRV RNA at two sites that are distant from each other in the polyribonucleotide chain. A third form of the sTobRV RNA was mutated at both sites. Multimeric forms of the one-site mutants of sTobRV(+)RNA and sTobRV(−)RNA showed, respectively, undiminished and slightly diminished self-cleavage, whereas the spontaneous circularization of each one-site-mutated, unit-length sTobRV(−)RNA was greatly reduced, compared to the reactions of wild-type sTobRV RNA and the two-site mutant. The two-site mutant and the wild-type sTobRV RNAs replicated with similar efficiency. They reduced the titer of, and severity of, symptoms induced by coinoculated Tobacco Ringspot Virus (TobRV). When coinoculated with TobRV, neither one-site mutant increased or provided protection against TobRV. Rather, each induced a substantial accumulation of what is apparently an endogenous form of sTobRV RNA. Our results are consistent with the formation of circular sTobRV(−)RNA as an essential step in sTobRV RNA replication.
Hans Van Tol - One of the best experts on this subject based on the ideXlab platform.
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trace amount of satellite rna associated with Tobacco Ringspot Virus increase stimulated by nonaccumulating satellite rna mutants
Virology, 1995Co-Authors: B K Passmore, Hans Van Tol, Jamal M. Buzayan, D Stabinsky, George BrueningAbstract:The small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) is dependent on Tobacco Ringspot Virus (TRSV) for replication and encapsidation. sTRSV RNA has appeared during serial passage of certain TRSV strains in some hosts. Co-inoculation of bean with TRSV and either of two related, nonaccumulating mutants of sTRSV RNA induced the appearance of sTRSV RNA in a single passage (van Tol et al., 1991, Virology 180, 23-30). The sTRSV RNA obtained after serial passage and after co-inoculation have the same nucleotide sequence, designated the endogenous sequence. The endogenous sTRSV RNA nucleotide sequence differs from that of each of the nonaccumulating sTRSV RNA at three positions. In order to detect possible trace amounts of endogenous satellite RNA in virion RNA preparations, RNA from two TRSV isolates was subjected to reverse transcription and polymerase chain reaction of the transcript (RT-PCR), using primers with sTRSV RNA terminal sequences. The yield of RT-PCR product suggests that the virion RNA preparations contained approximately 0.1 fg of sTRSV RNA per microgram of virion RNA. The nucleotide sequence of the RT-PCR product corresponded to that of the endogenous sTRSV RNA. The endogenous sTRSV RNA of TRSV inocula appears to be latent, being maintained in very small amounts during serial passage of TRSV in some hosts but capable of dramatic increase during serial passage in other hosts or when TRSV was co-inoculated with either of two specific sTRSV RNA mutants. Ten other nonaccumulating sTRSV RNA mutants did not induce a detected increase in sTRSV RNA.
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increase of satellite Tobacco Ringspot Virus rna initiated by inoculating circular rna
Virology, 1995Co-Authors: Jamal M. Buzayan, Hans Van Tol, Pierre Zalloua, George BrueningAbstract:Abstract A small satellite RNA of Tobacco Ringspot Virus (sTRSV RNA) generates circular and linear molecules of unit length and repetitive sequence, linear multimers during replication. The phosphodiester junction joining the unit satellite RNA sequences in multimeric and circular RNA resisted base-catalyzed cleavage in circles but not in linear dimers. We postulate that junctions of multimeric satellite RNA form during synthesis of the polyribonucleotide chain, whereas those of circular RNA result from a ligation reaction that introduces a group blocking the junction 2′-hydroxyl. To test the relative effectiveness of linear and circular satellite RNAs in initiating replication, we inoculated onto bean ( Phaseolus vulgaris cv Black Valentine) the four possible pairs of satellite RNA molecules, one member of each pair having the wild-type sTRSV RNA sequence and the other that of the replicating mutant 51AG/212CU, with each sequence provided as the unit circular or linear form. The relative amounts of wild-type and mutant satellite RNA sequence recovered from progeny virions reflected their relative abundances in the inoculum without regard to whether the sequence was supplied as a linear or a circular molecule. These results are consistent with models for the replication of the satellite RNA in which a circular form of the satellite RNA is a template for rolling circle transcription or is otherwise a replication intermediate or is readily converted to an intermediate. We also show that a circular form of a nonaccumulating satellite RNA mutant induced an increase in a satellite RNA that is endogenous to some Tobacco Ringspot Virus virion preparations, as demonstrated previously for the linear form.
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evidence for spontaneous circle formation in the replication of the satellite rna of Tobacco Ringspot Virus
Virology, 1991Co-Authors: Hans Van Tol, Jamal M. Buzayan, George BrueningAbstract:Abstract Replication of the satellite RNA of Tobacco Ringspot Virus (sTobRV RNA) has been postulated to require rolling circle transcription. The expected product of rolling circle transcription, multimeric sTobRV RNA, is known to undergo self-cleavage in vitro to release unit-length sTobRV RNA. A spontaneous, efficient, not enzymically-catalyzed in vitro circularization reaction is characteristic of unit-length sTobRV RNA of the less abundant, (−) polarity. We mutated sTobRV RNA at two sites that are distant from each other in the polyribonucleotide chain. A third form of the sTobRV RNA was mutated at both sites. Multimeric forms of the one-site mutants of sTobRV(+)RNA and sTobRV(−)RNA showed, respectively, undiminished and slightly diminished self-cleavage, whereas the spontaneous circularization of each one-site-mutated, unit-length sTobRV(−)RNA was greatly reduced, compared to the reactions of wild-type sTobRV RNA and the two-site mutant. The two-site mutant and the wild-type sTobRV RNAs replicated with similar efficiency. They reduced the titer of, and severity of, symptoms induced by coinoculated Tobacco Ringspot Virus (TobRV). When coinoculated with TobRV, neither one-site mutant increased or provided protection against TobRV. Rather, each induced a substantial accumulation of what is apparently an endogenous form of sTobRV RNA. Our results are consistent with the formation of circular sTobRV(−)RNA as an essential step in sTobRV RNA replication.
Sarabjot Singh - One of the best experts on this subject based on the ideXlab platform.
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expression of Tobacco Ringspot Virus capsid protein and satellite rna in insect cells and three dimensional structure of Tobacco Ringspot Virus like particles
Virology, 1995Co-Authors: Sarabjot Singh, Rosalba Rothnagel, B Venkataram V Prasad, Becky BuckleyAbstract:The capsid protein gene of Tobacco Ringspot Virus (TobRV), which had been modified to contain an amino-terminal methionine codon, was ligated into a baculoVirus transfer vector downstream from the polyhedrin promoter. The resulting plasmid was cotransfected with linearized baculoVirus DNA into insect cells. Recombinant baculoVirus expressed high levels of the TobRV capsid protein that assembled to form Virus-like particles that were similar in size and shape to authentic TobRV capsids. These Virus-like particles did not encapsidate any RNA, including the capsid protein mRNA. The capsid protein mRNA is a truncated RNA 2, which may lack a putative encapsidation signal. To determine whether an intact packaging substrate could be encapsidated by the TobRV capsid protein, another recombinant baculoVirus, concomitantly expressing both capsid protein and TobRV satellite RNA, was constructed. Surprisingly, the vast majority of the satellite RNA molecules expressed from this recombinant baculoVirus were ligated in the insect cells to form circular RNA molecules. Like circular forms of satellite RNA generated in planta, these circular satellite molecules remained unencapsidated by the TobRV capsid protein. Computer-generated three-dimensional reconstruction using electron cryomicrographs of the empty Virus-like particles allowed the first structural analyses of any nepoVirus capsid. This 22-A resolution reconstruction resembled capsids of other members of the picornaVirus superfamily. These data support the hypothesis that the nepoVirus capsid is structurally analogous to those of the como- and picornaViruses.
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Nucleotide sequence and in vitro expression of the capsid protein gene of Tobacco Ringspot Virus.
Virus Research, 1993Co-Authors: Becky Buckley, Sandra Silva, Sarabjot SinghAbstract:The nucleotide sequence of the 3' terminal 2022 nucleotides (nt) of Tobacco Ringspot Virus (TobRV) RNA 2 has been determined. Protein microsequence analysis of the amino-terminal residues of purified capsid protein localized the capsid protein gene between nt 2014 and 583 (from the 3' terminus) of this sequence. The proteolytic cleavage site that is processed to liberate the capsid protein from the RNA 2-encoded polyprotein was identified as Cys-Ala. The predicted translation product from the gene is a 477 amino acid long polypeptide with a calculated MW of 53 kDa. The gene was modified at the 5' end to facilitate sub-cloning, and to provide it with a methionine initiation codon. The modified gene was sub-cloned, transcribed in vitro and expressed in a rabbit reticulocyte lysate translation system, where it directed the synthesis of a 53 kDa polypeptide. Garnier-Osguthorpe-Robson analyses of the secondary structure of the capsid protein predicted the presence of three beta sheet domains, which suggests that this nepoVirus capsid may be structurally analogous to those of the como- and picornaViruses. These and other results from computer analyses of the nucleic acid and amino acid sequences, and comparisons with the capsid proteins of nepoViruses and other related Viruses are discussed.
O P Sehgal - One of the best experts on this subject based on the ideXlab platform.
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lipid peroxidation and superoxide production in cowpea vigna unguiculata leaves infected with Tobacco Ringspot Virus or southern bean mosaic Virus
Physiological and Molecular Plant Pathology, 1993Co-Authors: F Beleid I Elmoshaty, Sharon Pike, Anton Novacky, O P SehgalAbstract:Abstract The role of lipid peroxidation during Virus-induced necrotic hypersensitive reaction and nonnecrotic infection was studied in cowpea (Vigna unguiculata) leaves infected, respectively, with Tobacco Ringspot Virus (TRSV) and southern bean mosaic Virus-cowpea strain (SBMV). In TRSV-infected tissue, increased lipid peroxidation was detected 12 h prior to any significant potassium efflux and 9 h before local lesion appearance. Lipid peroxidation increased during lesion development, declining at 72 h after infection, the time of tissue collapse. Elevated superoxide production and superoxide dismutase activity paralleled the increase in lipid peroxidation. Lesion production was inhibited by pretreatment with superoxide dismutase or the free radical scavengers AET (2-aminoethylisothiouronium bromide hydrobromide) and Tiron (4,5-dihydroxy-1,3-benzenedisulphonic acid). In nonnecrotic SBMV infection, levels of lipid peroxidation were lower than those in the TRSV-infected plants, but above those of the control tissue. Lipoxygenase and catalase activities were not different from the control in either the necrotic or the nonnecrotic infections. While lipid peroxidation in Virus-induced hypersensitive reaction appears to be a critical component of symptom development, it may result from the Virus-induced accelerated senescence during nonnecrotic infection.
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ultrastructure of Tobacco Ringspot Virus induced local lesions in lima bean leaves
Journal of Phytopathology, 1993Co-Authors: J A White, O P SehgalAbstract:Tobacco Ringspot Virus (TRSV), a nepoVirus, induced unusually large, expanding lesions in the primary leaves of lima bean (Phaseolus lunatus cv. Nemagreen). During the course of lesion development, two phases were identified on the basis of ultrastructural observations. In the primary phase, cytological changes followed a pattern that was characteristic of compatible or systemic nepoVirus infections. Such changes included the formation of large, membranous inclusion bodies in the cytoplasm of mesophyll parenchyma and the accumulation of phytoferritin in the stroma of chloroplasts. The cells maintained their structural integrity and appeared metabolically active. The secondary phase was degradative in nature. Ultrastructural changes observed during this phase were representative of those that occur in a Virus-induced incompatible or hypersensitive (necrotic) reaction. Such changes included rounding of chloroplasts, vesiculation and disintegration of the plasma membrane and tonoplast, degeneration of cell organelles, and generalized plasmolysis. Subsequently, the cell walls collapsed, developing folds and loops around the shrunken cytosol. The collective result of these two ultrastructurally distinctive phases was the production of large necrotic lesions in the inoculated leaf, but no systemic viral spread.
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pathogenesis related proteins in lima bean leaves infected with Tobacco Ringspot Virus and their distribution within and around local lesions
Plant Cell Reports, 1992Co-Authors: O P SehgalAbstract:Tobacco Ringspot Virus (TRSV) induces circular, darkbrown local lesions on primary leaves of lima bean (Phaseolus lunatus cv Nemagreen) with a concomitant production of three basic and three acidic pathogenesisrelated (PR) proteins. The three basic proteins are: a 21 kDa protein related serologically to Pinto bean PR-4d and Tobacco PR-5 proteins; a 36 kDa glucanase that is related to Tobacco PR-2; and, a 31 kDa chitinase related serologically to ethylene-induced bean chitinase. The three acidic 18 kDa lima bean PR proteins are serologically similar and probably are charged isomers of the same protein. The 21 kDa basic protein and the 18 kDa acidic protein accumulated preferentially at the lesion center while the 31 kDa chitinase and TRSV were distributed evenly throughout the necrotic area. In green tissue immediately surrounding a lesion, the amounts of PR proteins were comparable to or lower than those in the necrotic area, and virions were not detected. This mode of spatial distribution indicates that lima bean PR proteins are not involved in TRSV localization, and is consistent with other observations that PR proteins play no direct role in restricting viral spread.
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induction of bean pr 4d type protein in divergent plant species after infection with Tobacco Ringspot Virus and its relationship with Tobacco pr 5
Phytopathology, 1991Co-Authors: O P Sehgal, R Rieger, F MohamedAbstract:A pathogenesis-related (PR) protein, immunologically related to the 21-kDa Pinto bean PR-4d protein, was induced in 20 plant species from six dicotyledonous families after infection with Tobacco Ringspot Virus. This protein was also induced in lima bean plants upon treatment with mercuric chloride, 2-chloroethylphosphonic acid, and benzoic acid. PR-4d protein was present in most plant species that developed necrotic symptoms, but there was no correlation between its induction and the types of symptoms produced. The Pinto bean PR-4d and Samsun NN Tobacco PR-5 proteins were reciprocally immunoreactive (...)