The Experts below are selected from a list of 1821 Experts worldwide ranked by ideXlab platform
Cécile Desbiez - One of the best experts on this subject based on the ideXlab platform.
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Papaya Ringspot Virus (Potyviridae)
2020Co-Authors: Cécile Desbiez, Hervé LecoqAbstract:Papaya Ringspot Virus (PRSV), a species member of the genus PotyVirus in the family Potyviridae, causes severe damage on cucurbit crops such as squash and melons, and worldwide damage on Papaya, a widely grown tropical fruit crop. Leaves of infected plants show mosaic symptoms and are often distorted and shoestring in shape, and infected plants are stunted. Fruit from infected plants can be malformed and show bumps, and infected Papaya fruit often show Ringspot symptoms, from which the name is derived. PRSV is grouped into type P or type W biotypes based on their host range. The P biotype infects cucurbits and Papaya, while the W biotype infects only cucurbits. The Virus is transmitted in a non-persistent manner by at least 24 aphid species. Phylogenetic analyzes suggest that PRSV originated in India and spread subsequently to Asia and America. Several Viruses closely related biologically and molecularly to PRSV form a common “PRSV cluster”. The worldwide impact of the other Viruses is much lower than for PRSV, although they can be locally important or emerging. Control of PRSV consists mostly in prophylactic measures and the use of resistant plants when they are available. Genetically engineered Papaya expressing the coat protein gene of PRSV are resistant to the Virus and are used commercially in Hawaii, one of only two cases for using commercial transgenic Virus-resistant crops in the US.
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New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage
2017Co-Authors: Cécile Desbiez, G Dafalla, Gustavo Romay, Pauline Millot, Catherine Wipf-scheibel, Hervé LecoqAbstract:New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage. 16. Rencontres de Virologie Végétale (RVV 2017)
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New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage
Virus Research, 2017Co-Authors: Cécile Desbiez, G Dafalla, Pauline Millot, Catherine Wipf-scheibel, Eric Verdin, Hervé LecoqAbstract:The “Papaya Ringspot Virus (PRSV) cluster” of cucurbit-infecting potyViruses contains five acknowledged species that have similar biological, serological and molecular properties. Additional data suggest there are other uncharacterized species from various locations in the world that likely belong to the PRSV cluster including a new PRSV-like Virus reported from Sudan in 2003. Molecular and biological data indicated that the Virus from Sudan belongs to a new species, tentatively named wild melon vein banding Virus (WMVBV). The complete nucleotide sequence of a second Virus from Sudan revealed it was a divergent relative of Moroccan watermelon mosaic Virus (MWMV). Based on sequence similarity this Virus was determined to be a distinct species and tentatively named Sudan watermelon mosaic Virus (SuWMV). Molecular analyses indicate that SuWMV is a recombinant between WMVBV- and MWMV-related Viruses. Based on surveys performed in Sudan between 1992 and 2012, SuWMV appeared 10 times more frequent than WMVBV in that country (14.6% vs. 1.5% of the samples tested). The geographic structure and molecular diversity patterns of the putative and acknowledged species suggest that the PRSV-like cluster originated in the Old World about 3600 years ago, with an important diversification in Africa.
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zucchini tigre mosaic Virus is a distinct potyVirus in the Papaya Ringspot Virus cluster molecular and biological insights
Archives of Virology, 2014Co-Authors: Gustavo Romay, H Lecoq, Cécile DesbiezAbstract:In recent years, three new potyViruses have been described in the Papaya Ringspot Virus (PRSV) cluster. In addition, two types of PRSV are recognized, type W, infecting cucurbit plants, and type P, infecting Papaya and also cucurbits. A third type, PRSV-T, was also partially described in Guadeloupe. Complete genome sequencing of four PRSV-T isolates showed that this Virus is a related Virus that is distinct from PRSV, and the name zucchini tigre mosaic Virus (ZTMV) is proposed, in reference to the typical symptoms observed in zucchini squash. Eleven other viral isolates from different geographic origins were confirmed as ZTMV isolates using the complete sequence of the cylindrical inclusion (CI) coding region, whereas pairwise sequence similarities in the coat protein (CP) coding region did not unambiguously distinguish ZTMV isolates from PRSV isolates. The use of the CI coding region for species demarcation appears more suitable than the CP coding region for closely related Viruses. Principal coordinates analysis based on the biological behavior of the viral isolates studied clustered PRSV-P, PRSV-W and ZTMV isolates into three different groups. Therefore, ZTMV is different from PRSV in its molecular and biological properties.
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potential involvement of melon fruit in the long distance dissemination of cucurbit potyViruses
Plant Disease, 2003Co-Authors: H Lecoq, Cécile Desbiez, C Wipfscheibel, M GirardAbstract:ABSTRACT Papaya Ringspot Virus (PRSV) and Zucchini yellow mosaic Virus(ZYMV) are potyViruses frequently reported in cucurbits in Mediterranean, subtropical, and tropical regions. Occasionally, epidemics are also observed in more temperate regions, but the ways these Viruses are introduced into new areas are not yet fully determined. We investigated the possibility that infected imported melon fruit could be a route for the introduction of PRSV and ZYMV. Imported melon fruits of the yellow canary type infected by ZYMV and PRSV were exposed in the fields next to healthy melon or squash bait plants. During this period, aphids were observed landing and probing on the fruits. In four independent experiments using different fruits, 3.1 to 25% of bait plants were infected by ZYMV and/or PRSV. PRSV was more frequently transmitted to bait plants than ZYMV. Comparison of partial sequences of the isolates from fruits and from bait plants showed a very high, if not complete, identity within each experiment, confirmin...
Dennis Gonsalves - One of the best experts on this subject based on the ideXlab platform.
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Papaya Ringspot Virus p characteristics pathogenicity sequence variability and control
Molecular Plant Pathology, 2008Co-Authors: Savarni Tripathi, Stephen A Ferreira, Jon Y. Suzuki, Dennis GonsalvesAbstract:SUMMARY Taxonomy: Papaya Ringspot Virus (PRSV) is an aphidtransmitted plant Virus belonging to the genus PotyVirus , family Potyviridae , with a positive sense RNA genome. PRSV isolates belong to either one of two major strains, P or W. The P strains infect both Papaya and cucurbits whereas the W strains infect only cucurbits.
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development of Virus resistant transgenic Papayas expressing the coat protein gene from a brazilian isolate of Papaya Ringspot Virus
Fitopatologia Brasileira, 2005Co-Authors: Manoel Teixeira Souza, Osmar Nickel, Dennis GonsalvesAbstract:Versoes traduziveis e nao traduziveis do gene da capa proteica (cp) de um isolado de Papaya Ringspot Virus (PRSV) coletado no Estado da Bahia, Brasil, foram produzidas para expressao nas variedades Sunrise e Sunset Solo de mamoeiro (Carica Papaya). O sistema de biobalistica foi utilizado para transformar embrioes somaticos secundarios derivados de embrioes zigoticos imaturos. Cinquenta e quatro linhas transgenicas, sendo 26 contendo versoes traduziveis e 28 contendo versoes nao traduziveis do gene cp foram regeneradas, o que resultou em 2,7% de eficiencia de transformacao, quando considerado o numero de linhas transgenicas obtidas por embriao zigotico imaturo excisado. Desafios de plantas R0 com PRSV BR, PRSV HA ou PRSV TH, respectivamente isolado brasileiro, havaiano e tailandes, revelaram linhas com resistencia a um, dois e tres isolados de PRSV. Apos analises moleculares e avaliacao agronomica preliminar, 13 populacoes R1 e R2 de mamoeiros transgenicos foram incorporadas ao programa de melhoramento genetico da Embrapa Mandioca e Fruticultura, em Cruz das Almas, Bahia, Brasil.
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development of transgenic Papayas expressing the coat protein gene from a brazilian isolate of Papaya Ringspot Virus prsv desenvolvimento de mamoeiros transgenicos resistentes a Virus expressando o gene da capa proteica de um isolado brasileiro de Papaya Ringspot Virus
Fitopatologia Brasileira, 2005Co-Authors: Manoel Teixeira Souza, Osmar Nickel, Dennis GonsalvesAbstract:Translatable and nontranslatable versions of the coat protein (cp) gene of a Papaya Ringspot Virus (PRSV) isolate collected in the state of Bahia, Brazil, were engineered for expression in Sunrise and Sunset Solo varieties of Papaya (Carica Papaya). The biolistic system was used to transform secondary somatic embryo cultures derived from immature zygotic embryos. Fifty-four transgenic lines, 26 translatable and 28 nontranslatable gene versions, were regenerated, with a transformation efficiency of 2.7%. Inoculation of cloned R0 plants with PRSV BR, PRSV HA or PRSV TH, Brazilian, Hawaiian and Thai isolates, respectively, revealed lines with mono-, double-, and triple-resistance. After molecular analysis and a preliminary agronomic evaluation, 13 R1 and R2 populations were incorporated into the Papaya-breeding program at Embrapa Cassava and Tropical Fruits, in Cruz das Almas, Bahia, Brazil
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engineered resistance against Papaya Ringspot Virus in venezuelan transgenic Papayas
Plant Disease, 2004Co-Authors: Gustavo Fermin, Valentina Inglessis, Cesar Garboza, Sairo Rangel, Manuel Dagert, Dennis GonsalvesAbstract:Fermin, G., Inglessis, V., Garboza, C., Rangel, S., Dagert, M., and Gonsalves, D. 2004. Engineered resistance against Papaya Ringspot Virus in Venezuelan transgenic Papayas. Plant Dis. 88:516-522. Local varieties of Papaya grown in the Andean foothills of Merida, Venezuela, were transformed independently with the coat protein (CP) gene from two different geographical Papaya Ringspot Virus (PRSV) isolates, designated VE and LA, via Agrobacterium tumefaciens. The CP genes of both PRSV isolates show 92 and 96% nucleotide and amino acid sequence similarity, respectively. Four PRSV-resistant R0 plants were intercrossed or selfed, and the progenies were tested for resistance against the homologous isolates VE and LA, and the heterologous isolates HA (Hawaii) and TH (Thailand) in greenhouse conditions. Resistance was affected by sequence similarity between the transgenes and the challenge Viruses: resistance values were higher for plants challenged with the homologous isolates (92 to 100% similarity) than with the Hawaiian (94% similarity) and, lastly, Thailand isolates (88 to 89% similarity). Our results show that PRSV CP gene effectively protects local varieties of Papaya against homologous and heterologous isolates of PRSV.
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Virus coat protein transgenic Papaya provides practical control of Papaya Ringspot Virus in hawaii
Plant Disease, 2002Co-Authors: Stephen A Ferreira, Maureen M. M. Fitch, Karen Y Pitz, Richard M. Manshardt, Dennis GonsalvesAbstract:Since 1992, Papaya Ringspot Virus (PRSV) destroyed nearly all of the Papaya hectarage in the Puna district of Hawaii, where 95% of Hawaii's Papayas are grown. Two field trials to evaluate transgenic resistance (TR) were established in Puna in October 1995. One trial included the following: SunUp, a newly named homozygous transformant of Sunset; Rainbow, a hybrid of SunUp, the nontransgenic Kapoho cultivar widely grown in Puna, and 63-1, another segregating transgenic line of Sunset. The second trial was a 0.4-ha block of Rainbow, simulating a near-commercial planting. Both trials were installed within a matrix of Sunrise, a PRSV-susceptible sibling line of Sunset. The matrix served to contain and trace pollen flow from TR plants, and as a secondary inoculum source. Virus infection was first observed 3.5 months after planting. At a year, 100% of the non-TR control and 91% of the matrix plants were infected, while PRSV infection was not observed on any of the TR plants. Fruit production data of SunUp and Rainbow show that yields were at least three times higher than the industry average, while maintaining percent soluble solids above the minimum of 11% required for commercial fruit. These data suggest that transgenic SunUp and Rainbow, homozygous and hemizygous for the coat protein transgene, respectively, offer a good solution to the PRSV problem in Hawaii.
Hervé Lecoq - One of the best experts on this subject based on the ideXlab platform.
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Papaya Ringspot Virus (Potyviridae)
2020Co-Authors: Cécile Desbiez, Hervé LecoqAbstract:Papaya Ringspot Virus (PRSV), a species member of the genus PotyVirus in the family Potyviridae, causes severe damage on cucurbit crops such as squash and melons, and worldwide damage on Papaya, a widely grown tropical fruit crop. Leaves of infected plants show mosaic symptoms and are often distorted and shoestring in shape, and infected plants are stunted. Fruit from infected plants can be malformed and show bumps, and infected Papaya fruit often show Ringspot symptoms, from which the name is derived. PRSV is grouped into type P or type W biotypes based on their host range. The P biotype infects cucurbits and Papaya, while the W biotype infects only cucurbits. The Virus is transmitted in a non-persistent manner by at least 24 aphid species. Phylogenetic analyzes suggest that PRSV originated in India and spread subsequently to Asia and America. Several Viruses closely related biologically and molecularly to PRSV form a common “PRSV cluster”. The worldwide impact of the other Viruses is much lower than for PRSV, although they can be locally important or emerging. Control of PRSV consists mostly in prophylactic measures and the use of resistant plants when they are available. Genetically engineered Papaya expressing the coat protein gene of PRSV are resistant to the Virus and are used commercially in Hawaii, one of only two cases for using commercial transgenic Virus-resistant crops in the US.
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New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage
2017Co-Authors: Cécile Desbiez, G Dafalla, Gustavo Romay, Pauline Millot, Catherine Wipf-scheibel, Hervé LecoqAbstract:New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage. 16. Rencontres de Virologie Végétale (RVV 2017)
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New species in the Papaya Ringspot Virus cluster: insights into the evolution of the PRSV lineage
Virus Research, 2017Co-Authors: Cécile Desbiez, G Dafalla, Pauline Millot, Catherine Wipf-scheibel, Eric Verdin, Hervé LecoqAbstract:The “Papaya Ringspot Virus (PRSV) cluster” of cucurbit-infecting potyViruses contains five acknowledged species that have similar biological, serological and molecular properties. Additional data suggest there are other uncharacterized species from various locations in the world that likely belong to the PRSV cluster including a new PRSV-like Virus reported from Sudan in 2003. Molecular and biological data indicated that the Virus from Sudan belongs to a new species, tentatively named wild melon vein banding Virus (WMVBV). The complete nucleotide sequence of a second Virus from Sudan revealed it was a divergent relative of Moroccan watermelon mosaic Virus (MWMV). Based on sequence similarity this Virus was determined to be a distinct species and tentatively named Sudan watermelon mosaic Virus (SuWMV). Molecular analyses indicate that SuWMV is a recombinant between WMVBV- and MWMV-related Viruses. Based on surveys performed in Sudan between 1992 and 2012, SuWMV appeared 10 times more frequent than WMVBV in that country (14.6% vs. 1.5% of the samples tested). The geographic structure and molecular diversity patterns of the putative and acknowledged species suggest that the PRSV-like cluster originated in the Old World about 3600 years ago, with an important diversification in Africa.
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biological and molecular characterization of moroccan watermelon mosaic Virus and a potyVirus isolate from eastern sudan
Plant Disease, 2001Co-Authors: Hervé Lecoq, Cécile Desbiez, G Dafalla, C Wipfscheibel, B Delecolle, Tanya Lanina, Zakir Ullah, Rebecca GrumetAbstract:A potyVirus (Su-94-54) was isolated from a naturally infected snake cucumber (Cucumis melo var. flexuosus) plant with severe mosaic and leaf deformation symptoms collected in Eastern Sudan. This isolate has a host range limited to cucurbits and is serologically distantly related to Moroccan watermelon mosaic Virus (MWMV) and to Papaya Ringspot Virus (PRSV). Coat protein sequence analysis of Su-94-54 and MWMV and comparison with other potyViruses indicate that Su-94-54 is more closely related to MWMV than to any other potyVirus. Based on the amino acid sequence identity in the core part of the coat protein with MWMV (86%), this isolate could be regarded as a distinct species. However, because of biological, cytological, and serological affinities with MWMV, we propose that this isolate be considered as a strain of MWMV, possibly an evolutionary intermediate between MWMV and PRSV, until more is known on the structure of the PRSV subgroup within the genus PotyVirus.
Shyidong Yeh - One of the best experts on this subject based on the ideXlab platform.
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generation of transgenic watermelon resistant to zucchini yellow mosaic Virus and Papaya Ringspot Virus type w
Plant Cell Reports, 2011Co-Authors: Chuhui Chiang, Chingfu Yang, Junhan Chen, Yuwen Chen, Shyidong YehAbstract:Zucchini yellow mosaic Virus (ZYMV) and Papaya Ringspot Virus type W (PRSV W) are major limiting factors for production of watermelon worldwide. For the effective control of these two Viruses by transgenic resistance, an untranslatable chimeric construct containing truncated ZYMV coat protein (CP) and PRSV W CP genes was transferred to commercial watermelon cultivars by Agrobacterium-mediated transformation. Using our protocol, a total of 27 putative transgenic lines were obtained from three cultivars of ‘Feeling’ (23 lines), ‘China baby’ (3 lines), and ‘Quality’ (1 line). PCR and Southern blot analyses confirmed that the chimeric construct was incorporated into the genomic DNA of the transformants. Greenhouse evaluation of the selected ten transgenic lines of ‘Feeling’ cultivar revealed that two immune lines conferred complete resistance to ZYMV and PRSV W, from which Virus accumulation were not detected by Western blotting 4 weeks after inoculation. The transgenic transcript was not detected, but small interfering RNA (siRNA) was readily detected from the two immune lines and T1 progeny of line ZW 10 before inoculation, indicating that RNA-mediated post-transcriptional gene silencing (PTGS) is the underlying mechanism for the double-Virus resistance. The segregation ratio of T1 progeny of the immune line ZW10 indicated that the single inserted transgene is nuclearly inherited and associated with the phenotype of double-Virus resistance as a dominant trait. The transgenic lines derived from the commercial watermelon cultivars have great potential for control of the two important Viruses and can be implemented directly without further breeding.
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Transgene-specific and event-specific molecular markers for characterization of transgenic Papaya lines resistant to Papaya Ringspot Virus.
Transgenic research, 2009Co-Authors: Ming Jen Fan, Yi-jung Kung, Shu Chen, Ying-huey Cheng, Huey-jiunn Bau, Shyidong YehAbstract:The commercially valuable transgenic Papaya lines carrying the coat protein (CP) gene of Papaya Ringspot Virus (PRSV) and conferring Virus resistance have been developed in Hawaii and Taiwan in the past decade. Prompt and sensitive protocols for transgene-specific and event-specific detections are essential for traceability of these lines to fulfill regulatory requirement in EU and some Asian countries. Here, based on polymerase chain reaction (PCR) approaches, we demonstrated different detection protocols for characterization of PRSV CP-transgenic Papaya lines. Transgene-specific products were amplified using different specific primer pairs targeting the sequences of the promoter, the terminator, the selection marker, and the transgene, and the region across the promoter and transgene. Moreover, after cloning and sequencing the DNA fragments amplified by adaptor ligation-PCR, the junctions between plant genomic DNA and the T-DNA insert were elucidated. The event-specific method targeting the flanking sequences and the transgene was developed for identification of a specific transgenic line. The PCR patterns using primers designed from the left or the right flanking DNA sequence of the transgene insert in three selected transgenic Papaya lines were specific and reproducible. Our results also verified that PRSV CP transgene is integrated into transgenic Papaya genome in different loci. The copy number of inserted T-DNA was further confirmed by real-time PCR. The event-specific molecular markers developed in this investigation are crucial for regulatory requirement in some countries and intellectual protection. Also, these markers are helpful for prompt screening of a homozygote-transgenic progeny in the breeding program.
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comparison of the nuclear inclusion b protein and coat protein genes of five Papaya Ringspot Virus strains distinct in geographic origin and pathogenicity
Phytopathology, 1994Co-Authors: C H Wang, H J Bau, Shyidong YehAbstract:A complementary DNA library was constructed to the genomic RNA of an isolate of Papaya Ringspot Virus (PRSV), PRSV YK (YK), that represents the most prevalent mosaic strain of Taiwan. A 2.96-kb clone, pYKB9, corresponding to the 3'-region of YK RNA was selected by immunoscreening with the antiserum to the coat protein (CP). The clone had 2,960 nucleotide residues and represented part of the nuclear inclusion a (NIa) gene, the complete nuclear inclusion b (NIb) gene, the entire CP gene, and the 3'-noncoding region of YK RNA. The nucleotide sequence was compared to those of the 3' regions of the published Hawaii severe strain, PRSV HA (HA), the Hawaii mild strain PRSV HA 5-1 (HA 5-1), the nonPapaya-infecting Florida strain, PRSV W(fl) (W(fl)), and the nonPapaya-infecting Australia strain PRSV W(aust) (W(aust))
Yi-jung Kung - One of the best experts on this subject based on the ideXlab platform.
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Generation of transgenic Papaya with double resistance to Papaya Ringspot Virus and Papaya leaf-distortion mosaic Virus.
Phytopathology, 2009Co-Authors: Yi-jung Kung, Yi-ling Wu, Chiung-huei Huang, Tsui-miao ChenAbstract:During the field tests of coat protein (CP)-transgenic Papaya lines resistant to Papaya Ringspot Virus (PRSV), another PotyVirus sp., Papaya leaf-distortion mosaic Virus (PLDMV), appeared as an emerging threat to the transgenic Papaya. In this investigation, an untranslatable chimeric construct containing the truncated CP coding region of the PLDMV P-TW-WF isolate and the truncated CP coding region with the complete 3' untranslated region of PRSV YK isolate was transferred into Papaya (Carica Papaya cv. Thailand) via Agrobacterium-mediated transformation to generate transgenic plants with resistance to PLDMV and PRSV. Seventy-five transgenic lines were obtained and challenged with PRSV YK or PLDMV P-TW-WF by mechanical inoculation under greenhouse conditions. Thirty-eight transgenic lines showing no symptoms 1 month after inoculation were regarded as highly resistant lines. Southern and Northern analyses revealed that four weakly resistant lines have one or two inserts of the construct and accumulate detectable amounts of transgene transcript, whereas nine resistant lines contain two or three inserts without significant accumulation of transgene transcript. The results indicated that double Virus resistance in transgenic lines resulted from double or more copies of the insert through the mechanism of RNA-mediated posttranscriptional gene silencing. Furthermore, three of nine resistant lines showed high levels of resistance to heterologous PRSV strains originating from Hawaii, Thailand, and Mexico. Our transgenic lines have great potential for controlling a number of PRSV strains and PLDMV in Taiwan and elsewhere.
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Transgene-specific and event-specific molecular markers for characterization of transgenic Papaya lines resistant to Papaya Ringspot Virus.
Transgenic research, 2009Co-Authors: Ming Jen Fan, Yi-jung Kung, Shu Chen, Ying-huey Cheng, Huey-jiunn Bau, Shyidong YehAbstract:The commercially valuable transgenic Papaya lines carrying the coat protein (CP) gene of Papaya Ringspot Virus (PRSV) and conferring Virus resistance have been developed in Hawaii and Taiwan in the past decade. Prompt and sensitive protocols for transgene-specific and event-specific detections are essential for traceability of these lines to fulfill regulatory requirement in EU and some Asian countries. Here, based on polymerase chain reaction (PCR) approaches, we demonstrated different detection protocols for characterization of PRSV CP-transgenic Papaya lines. Transgene-specific products were amplified using different specific primer pairs targeting the sequences of the promoter, the terminator, the selection marker, and the transgene, and the region across the promoter and transgene. Moreover, after cloning and sequencing the DNA fragments amplified by adaptor ligation-PCR, the junctions between plant genomic DNA and the T-DNA insert were elucidated. The event-specific method targeting the flanking sequences and the transgene was developed for identification of a specific transgenic line. The PCR patterns using primers designed from the left or the right flanking DNA sequence of the transgene insert in three selected transgenic Papaya lines were specific and reproducible. Our results also verified that PRSV CP transgene is integrated into transgenic Papaya genome in different loci. The copy number of inserted T-DNA was further confirmed by real-time PCR. The event-specific molecular markers developed in this investigation are crucial for regulatory requirement in some countries and intellectual protection. Also, these markers are helpful for prompt screening of a homozygote-transgenic progeny in the breeding program.
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Potential Threat of a New Pathotype of Papaya leaf distortion mosaic Virus Infecting Transgenic Papaya Resistant to Papaya Ringspot Virus
Phytopathology, 2008Co-Authors: Yi-jung Kung, J. A. J. Raja, S.-j. Chan, K.-c. Chen, Y.-k. Chen, H.-w. WuAbstract:A Virus identified as a new pathotype of Papaya leaf distortion mosaic Virus (PLDMV, P-TW-WF) was isolated from diseased Papaya in an isolated test-field in central Taiwan, where transgenic Papaya lines resistant to Papaya Ringspot Virus (PRSV) were evaluated. The infected plants displayed severe mosaic, distortion and shoe-stringing on leaves; stunting in apex; and water-soaking on petioles and stems. This Virus, which did not react in enzyme-linked immunosorbent assay with the antiserum to the PRSV coat protein, infected only Papaya, but not the other 18 plant species tested. Virions studied under electron microscope exhibited morphology and dimensions of potyVirus particles. Reverse transcription-polymerase chain reaction conducted using potyVirus-specific primers generated a 1,927-nucleotide product corresponding to the 3' region of a potyVirus, showing high sequence identity to the CP gene and 3' noncoding region of PLDMV. Search for similar isolates with the antiserum against CP of P-TW-WF revealed scattered occurrence of PLDMV in Taiwan. Phylogenetic analysis of PLDMV isolates of Taiwan and Japan indicated that the Taiwan isolates belong to a separate genetic cluster. Since all the Taiwan isolates infected only Papaya, unlike the cucurbit-infecting Japanese P type isolates, the Taiwan isolates are considered a new pathotype of PLDMV. Susceptibility of all our PRSV-resistant transgenic Papaya lines to PLDMV indicates that the Virus is an emerging threat for the application of PRSV-resistant transgenic Papaya in Taiwan and elsewhere.
