Literatura científica selecionada sobre o tema "Tobacco ring spot virus"

108 sample Collected from the fields of farmers in the areas of apple cultivation in the south of Syria during the years 1998-2007, and the most important symptoms associated with infection were recorded, results of the biometric tests (mechanical inoculation on indicator plant) and examination by electron microscope and serological tests (ELISA) using antisera of Apple mosaic virus, Apple chlorotic leaf spot virus, Tomato ring spot virus , Tomato spotted wilt virus, Tobacco ring spot virus , Tomato black ring virus and Arabis mosaic virus to the spread of a virus infection of Apple chlorotic leaf spot virus (ACLSV) by 24%, Apple mosaic virus (ApMV) by 26.9% and to register cases Tomato ring spot virus (TomRSV) by 13% and Tobacco ring spot virus (TRSV) by %14.8, Tomato black ring virus (TBRV) rate of % 12.03 and Arabis mosaic virus (ArMV) 2.43% for the first time on apples in Syria, and the likelihood of several viral and viroid diseases, that we need to reassess the health situation in view of the importance of maintaining the cultivation of apples and recommended program documentation for the production of propagation of disease-free, with proposal to use molecular methods to detect and identify viral diseases causes and strains prevalent in Syria.

Tobacco rattle virus (TRV) is the type member of the Tobravirus genus which also includes pea early browning and pepper ringspot viruses. The ring spot disease of peony associated with TRV has been reported in Europe and Asia and recently in Alaska but the literature is sparse regarding reports of the disease in the US. These results represent the first confirmed report of TRV in peony in Ohio, and expand the known geographic distribution of the virus. Accepted for publication 26 June 2012. Published 11 July 2012.

Rubus ellipticus is a perennial shrub occurring in natural vegetation of the temperate and subtropical Himalayas. For several years, plants of R. ellipticus in and around the Institute of Himalayan Bioresource Technology in Palampur were seen with mild mosaic and chlorotic symptoms on leaves followed by necrotic ring spots. Infected plants often recovered from the symptoms. The causal agent was mechanically transmissible to several herbaceous hosts including Cucumis sativus, Chenopodium album, C. quinoa, Cucurbita maxima, C. pepo, Melilotus alba, Trifolium repens, and Zinnia elegans. The virus incited chlorotic local lesions followed by systemic necrotic lesions or ring spots and severe stunting on C. sativus. Several aphid species (Myzus persicae, Aphis gossypii, A.fabae-solanella, Brevicoryne brassicae, and Macrosiphoniella sanbornii) were tried as viral vectors, but all failed to transmit the virus. Virus has been detected in pollen and fruit of infected plants. Ilarvirus-like particles, 27 nm in diameter, were observed in partially purified extracts of symptomatic plants of R. ellipticus and in experimentally infected C. sativus plants, but not in healthy plants. The isolate was distantly serologically related to apple mosaic virus and unrelated to tobacco streak virus. Presence of Prunus necrotic ring spot virus (PNRSV) in symptomatic plants was also confirmed by enzyme-linked immunosorbent assay with antiserum from American Type Culture Collection and Agdia, Inc. (Elkhart, IN). This is the first report of a viral disease in R. ellipticus. The presence of PNRSV in a new weed host may become an important constraint to production of susceptible agronomic crops around Palampur.

Complexes of Cu(II), Ni(II) and Zn(II) with of 3-(phenyl)-1-(2’-hydroxynaphthyl) – 2 – propen – 1 – one (PHPO) , 3 - (4-chlorophenyl) - 1- (2’-hydroxynaphthyl)–2–propen – 1 – one (CPHPO), 3 - (4 -methoxyphenyl) -1-(2’-hydroxynapthyl)-2-propen-1-one(MPHPO),3 - (3,4-dimethoxyphenyl) –1-(2’-hydroxynaphthyl) – 2 - propen– 1 – one (DMPHPO) have been prepared and the purity of the samples were checked by elemental analysis. The ligands and their Cu(II), Ni(II) and Zn(II) complexes were tested on the infectivity of tobacco ring spot virus(TRSV) using cowpea (Vigna Sinensis) as a local lesions assay host. All the compounds were tested at different concentrations (250 ppm to 1500 ppm)on the infectivity of the virus by applying them either with virus inoculum or 24 h before of after virus inoculation to the test plants. The compounds were found to have varied effects on virus infectivity depending on compounds concentration and method of application. The statistical significance of the data was determined by using analysis of variance.

Tobacco rattle virus (TRV) causes the economically important corky ring spot disease in potato. Chemical control is difficult due to the soilborne nature of the TRV-transmitting nematode vector, and identifying natural host resistance against TRV is considered to be the optimal control measure. The present study investigated the sensitivity of 63 cultivars representing all market types (evaluated at North Dakota and Washington over 2 years) for the incidence of TRV-induced tuber necrosis and severity. This article also investigates the cultivar–location interaction (using a mixed-effects model) for TRV-induced necrosis. TRV-induced tuber necrosis (P < 0.0001) and severity (P < 0.0001) were significantly different among cultivars evaluated separately in North Dakota and Washington trials. Mixed-effects model results of pooled data (North Dakota and Washington) demonstrated that the interaction of cultivar and location had a significant effect (P = 0.03) on TRV-induced necrosis. Based on the virus-induced tuber necrosis data from both years and locations, cultivars were categorized into sensitive, moderately sensitive, insensitive, and moderately insensitive groups. Based on data from North Dakota, 10 cultivars, including Bintje, Centennial Russet, Ciklamen, Gala, Lelah, Oneida Gold, POR06V12-3, Rio Colorado, Russian Banana, and Superior, were rated as insensitive to TRV-induced tuber necrosis. Similar trials assessing TRV sensitivity among cultivars conducted in Washington resulted in a number of differences in sensitivity rankings compared with North Dakota trials. A substantial shift in sensitivity of some potato cultivars to TRV-induced tuber necrosis was observed between the two locations. Four cultivars (Centennial Russet, Oneida Gold, Russian Banana, and Superior) ranked as insensitive for North Dakota trials were ranked as sensitive for Washington trials. These results can assist the potato industry in making cultivar choices to reduce the economic impact of TRV-induced tuber necrosis.

The soybean aphid, Aphis glycines Matsamura (Hemiptera: Aphididae), is a pest of soybeans in the People's Republic of China, Korea, Thailand, Japan, North Borneo, Malaya, and the Philippines (Blackman and Eastop 2000). It was first identified in North America in 2000 from soybean fields in 10 states in the north-central United States of America, although the route of entry and time of introduction are not known (North Central Regional Pest Alert 2001). Dai and Fan (1991) reported that yield losses caused by soybean aphids on soybeans in the People's Republic of China were greater when the crop was infested soon after planting, and the presence of large populations of the aphid throughout the growing season resulted in 20%–30% yield losses. The soybean aphid can also transmit several viruses that infect soybeans in North America, including alfalfa mosaic, soybean mosaic, bean yellow mosaic, peanut mottle, peanut stunt, and peanut stripe (Hartman et al. 2001). In North America, the soybean aphid is known to transmit soybean mosaic virus and alfalfa mosiac virus (Hill et al. 2001). A survey of Ontario soybean fields revealed the presence of tobacco ring spot virus, soybean mosiac virus, and bean pod mottle virus (Michelutti et al. 2001); all of which could potentially be spread by this newly introduced aphid.

Viral diseases are the important diseases next to the fungal and bacterial in Nepal. The increase in incidence and severity of viral diseases and emergence of new viral diseases causes the significant yield losses of different crops in Nepal. But the research and studies on plant viral diseases are limited. Most of the studies were focused in viral diseases of rice (Rice tungro virus and Rice dwarf virus), tomato (Yellow leaf curl virus) and potato (PVX and PVY). Maize leaf fleck virus and mosaic caused by Maize mosaic virus were recorded as minor disease of maize. Citrus Tristeza Virus is an important virus of citrus fruit in Nepal while Papaya ringspot potyvirus, Ageratum yellow vein virus (AYVV), Tomato leaf curlJava betasatellite and Sida yellow vein Chinaalphasatellite were recorded from the papaya fruit. The Cucumber mosaic virus (CMV) and Zucchini yellow mosaic potyvirus (ZYMV) are the viral diseases of cucurbitaceous crop reported in Nepal. Mungbean yellow mosaic India virus (MYMIV) found to infect the many crops Limabean, Kidney bean, blackgram and Mungbean. Bean common mosaic necrosis virus in sweet bean, Pea leaf distortion virus (PLDV), Cowpea aphid‐borne mosaic potyvirus (CABMV), Peanut bud necrosis virus (PBNV) in groundnut, Cucumber mosaic virus (CMV). Chili veinal mottle potyvirus (CVMV) and Tomatoyellow leaf curl gemini virus (TYLCV) were only reported and no any further works have been carried out. The 3 virus diseases Soyabean mosaic (SMV), Soybean yellow mosaic virus and Bud blight tobacco ring spot virus (TRSV) were found in soybean.Int. J. Appl. Sci. Biotechnol. Vol 6(2): 75-80

Dahlia (Dahlia variabilis Hort.) is a significant ornamental plant in New Zealand. Symptoms such as mosaic, ring spots, mottling, and veinal chlorosis, suggestive of a viral infection, are often seen in various dahlia collections. To better understand the incidence of viruses in dahlia in New Zealand, several popularly grown cultivars were evaluated for viruses that are known to infect dahlia. Viruses that were tested included Cucumber mosaic virus (CMV), Dahlia mosaic virus (DMV), Impatiens necrotic spot virus (INSV), Tobacco streak virus (TSV), and Tomato spotted wilt virus (TSWV). At least one symptomatic plant was tested from each of the following cultivars: Akito Dawn, Cincinnati Dancer, Hamari Accord, Hamari Rose, LeBatts Prime, LeVonne Splinter, Riverlea Tropicana, Spartacus, Tartan, Tui Connie, and Wandas Antartica. Except for DMV, initial testing was done by ELISA with commercially available kits for the above viruses. In the case of dahlia mosaic, samples were tested for DMV that was described previously (4) and two additional and distinct caulimoviruses (DMV-D10 and DMV-Holland) that were found to be associated with dahlia (1,2). Primer pairs, ORF6st: ATG GAA GAA ATT AAG GCG T and ORF6end: TTG TCT TCA TCC ATA AAG CAG; DenF1: CAG CAA GAA ACA GGA ATT GA and DenR: TTA CAG TCG AAG CTG CTA AA; and Kapht-F: ATG AGT AAT GCT TCA GCA A and Kapht-R: TGA CCA TGG CTT CTA ACT GT were used for the specific detection of DMV-D10, DMV-Holland, and DMV, respectively (1). None of the samples tested were ELISA positive for CMV, INSV, or TSWV. To verify the TSV infection, TSV-specific primers (5′-GTC CAG ACC ATC CAT CCA AC-3′ and 5′-TTG ATT CAC CAG GAA ATC TT-3′), designed based on sequences available in GenBank, were used in reverse transcription (RT)-PCR. For DMV, the diagnostic tests used were electron microscopy and PCR followed by amplicon cloning and sequencing. Electron microscopic observation of leaf-dip preparations showed near isometric virions, approximately 50 to 60 nm in all samples tested. PCR showed that all samples tested were positive for DMV-Holland and DMV-D10. While DMV-Holland is a typical caulimovirus, DMV-D10 was found to exist as an endogenous plant pararetroviral sequence in dahlia (3). One sample each from two cultivars, Spartacus and Tui Connie, were positive for TSV by ELISA, RT-PCR, followed by the sequence analysis of the cloned amplicon. The impact of TSV-infected dahlias as a potential source of inoculum remains to be seen. Our results suggested the prevalence of dahlia mosaic-associated caulimoviruses in several dahlia cultivars and the presence of TSV in New Zealand dahlias. Dahlia mosaic continues to be prevalent in several parts of the world (1), and with the current findings in New Zealand, testing for these viruses should be conducted to ensure virus-free status of the propagating material. References: (1) V. Pahalawatta et al. Plant Dis. 91:1194, 2007. (2) V. Pahalawatta et al. Arch. Virol.153:733, 2008. (3) V. Pahalawatta et al. Virology 376:253, 2008. (4) R. D. Richins and R. J. Shepherd. Virology 124:208, 1983.

There is limited information about the distribution of strawberry viruses in North America and around the world. Since the turn of the century, there has been a concerted effort to develop sensitive tests for many of the previously uncharacterized, graft-transmissible agents infecting strawberry. These tests were employed to determine the presence of strawberry viruses in major strawberry production and nursery areas of North America. The viruses evaluated in this study were Apple mosaic, Beet pseudo-yellows, Fragaria chiloensis latent, Strawberry chlorotic fleck, Strawberry crinkle, Strawberry latent ring spot, Strawberry mild yellow edge, Strawberry mottle, Strawberry necrotic shock, Strawberry pallidosis, Strawberry vein banding, and Tobacco streak. The aphid-borne viruses were predominant in the Pacific Northwest whereas the whitefly-borne viruses were prevalent in California, the Midwest, and the Southeast. In the Northeast, the aphid-transmitted Strawberry mottle and Strawberry mild yellow edge viruses along with the whitefly-transmitted viruses were most common. The incidence of pollen-borne viruses was low in most areas, with Strawberry necrotic shock being the most prevalent virus of this group. These results indicate that there are hotspots for individual virus groups that normally coincide with the presence of the vectors. The information presented highlights the high-risk viruses for nursery production, where efforts are made to control all viruses, and fruit production, where efforts are made to control virus diseases.

Cucumber (Cucumis sativus L.) and Gherkin (Cucumis anguria L.) are important cucurbitaceous vegetables grown in India for slicing and pickling. During the 2000 to 2002 rainy season and summer, a new virus disease, causing yield losses of 31 to 75% in Bangalore, Bellary, Davanagiree, and Tumkur districts of Karnataka State, infected cucumber and gherkin. Symptoms were tip necrosis characterized by necrotic lesions on leaves, and a general leaf and stem necrosis extending to mid veins, petioles, flower buds and tip, eventually resulting in dieback of vines. Tissue extracts from symptomatic leaves of cucumber and gherkin were mechanically inoculated on several herbaceous indicator plants (cowpea, cucumber, pepper, Zinnia, watermelon, Chenopodium amaranticolor, sunflower, Nicotiana glutinosa, N. tabacum, and Gomphrena globosa). On most hosts, symptoms of chlorotic or necrotic lesions followed by mottle or systemic necrosis were observed. Back-inoculation from the symptomatic indicator plants onto cucumber and gherkin resulted in symptoms typical of those observed in the field. Electron microscopic examination of leaf-dip preparation and ultra thin sections of virus infected plant samples showed the presence of isometric particles 25 to 28 nm in diameter. Similar types of particles were observed when infected samples were trapped in immunosorbent electron microscopy with polyclonal antibodies specific to Tobacco Streak virus (TSV) but not to Watermelon silver mottle virus (WSMV). Enzymelinked immunosorbent assay tests using leaf extracts of field-collected samples and sap-inoculated plants showed positive reaction to antibodies of TSV (1) but not to antibodies of Cucumber mosaic virus, WSMV, Watermelon bud necrosis virus, Papaya ring spot virus W strain, and Zucchini yellow mosaic virus. Reverse transcription-polymerase chain reaction (RT-PCR) of RNA extracts of infected samples of field and inoculated symptomatic plants was done by using primers derived from TSV RNA3 specific for the coat protein (CP) region of TSV (2). A 800-bp specific DNA fragment was amplified from infected cucumber and gherkin but not from healthy control plants. Sequence analysis of cloned PCR fragments revealed nucleotide identities of 99% with TSV isolates from cotton, mungbean, sunnhemp, and sunflower (GenBank Accessions Nos. AF515824, AF515823, AF515825, and AY061929) and 88% with TSV-WC (GenBank Accession No. X00435). On the basis of host range, serological relationship, electron microscopy, and sequence analysis of the CP region, the virus was identified as a strain of TSV. To our knowledge, this is the first report of natural occurrence of TSV on cucumber and gherkin in India. References: (1). A. I. Bhat et al. Arch. Virol. 147:651, 2002. (2). B. J. C. Cornelissen et al. Nucleic Acids Res.12:2427, 1984.

The technique of digital autocorrelation of intensity fluctuations of scattered laser light is used to investigate the aggregation behavior of carnation ringspot virus. It is hypothesized by the author that the aggregation rate (R) is given by [See Thesis for Equation] R is measured for a range of values of the dependent experimental variables, temperature (T), and virus concentration (v₀). And the dependence of the two aggregation parameters, the temperature of aggregation (T[sub c]) and the energy of aggregation (E[sub agg]), on the experimental variables is ascertained. Also certain physical properties of the virus are measured: size, molecular weight, and diffusion coefficient. The experimental accuracy of the apparatus is determined by performing a series of experiments on a known system of Latex spheres.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

碩士
亞洲大學
生物科技學系碩士班
99
Tospovirus, the only plant-infecting genus in the family Bunyaviridae, has enveloped virions of 80-110 nm in diameter consisting of three segmented single-stranded RNA genome, denoted S, M and L, for coding six viral proteins. Both S and M RNAs are ambisense and L RNA has a negative polarity. A nonstructural NSs protein, acting as gene-silencing suppressor, and the RNA-binding nucleocapsid protein (NP) are encoded from the S RNA. The M RNA is responsible for coding a nonstructural NSm protein involved in cell-to-cell movement and the precursor of two glycoproteins on the surface of viral envelope. The L RNA codes the RNA-dependent RNA polymerase (RdRp) for replication and transcription. Tomato yellow ring virus (TYRV), isolated from tomato in Iran, and Peanut chlorotic fan-spot virus (PCFV), from peanut in Taiwan, were classified as two tentative species of the genus Tospovirus. To clarify the taxonomic status of these two viruses, the M and L RNAs of TYRV and the M RNA of PCFV were determined and analyzed in this investigation. The M RNA of TYRV has 4786 nucleotides (nt) coding for a NSm protein of 308 amino acids (aa) (34.5 kDa) and a glycoprotein precursor (GP) of 1310 aa (128 kDa). The L RNA of TYRV has 8877 nt encoding an RdRp of 2873 aa (331 kDa). The M RNA of PCFV has 4786 nt encoding a NSm protein of 306 aa (34.3 kDa) and a GP of 1111 aa (126.3 kDa). The NSm and GP proteins of TYRV share high 89.9% and 80.1-86.5% aa identities, respectively, with those of Polygonum ringspot virus (PolRSV) and Iris yellow spot virus (IYSV). However, the NSm and GP proteins of PCFV share low identities of 34.6-42.7% and 31.1-33.3%, respectively, with those of other tospovirus species. The RdRp of TYRV shares the highest aa identity (88.7%) with that of IYSV. Sequence analyses indicate that TYRV and PCFV should be classified as official species of the genus Tospovirus. TYRV is closely related to IYSV and PolRSV, but PCFV is distant from other tospoviruses.

碩士
國立中興大學
植物病理學系
92
Abstract Transgenic papaya lines carrying Papaya ringspot virus (PRSV) coat protein (CP) gene were previously generated in our laboratory to confer resistance against PRSV infection. Recently, it was found that the resistance was overcome by Papaya leaf-distortion mosaic virus (PLDMV) that might be serious threat when the transgenic lines are practically applied in Taiwan. In this study, for the effective control of PRSV and PLDMV, an untranslatable chimeric construct containing truncated PRSV YK CP and PLDMV DL CP genes was transferred into papaya (Carica papaya cv. Thailand) via Agrobacterum-mediated transformation. A total of 75 transgenic lines was obtained and separately challenged with PRSV YK and PLDMV DL by mechanical inoculation under greenhouse conditions. Among them, 38 transgenic lines showed no symptoms one month after inoculation and were classified as resistant lines. Molecular analyses by Southern and northern blottings indicated that four sensitive lines have one insert of the construct and high amount of transgene transcript was detected, whereas the resistant lines have two or multiple inserts and no transgene transcript detected. A 3:1 ratio for the segregation of the transgene of resistant lines TPY16 12-4 and TPY16 15-5 were revealed by kanamycin assay using petioles of R1 plants derived from crossing with non-transgenic Sunrise papaya, indicating that the transgene of both lines located at two loci of chromosome. The results indicated that double resistance of transgenic lines is resulted from double or multiple copies of the insert and RNA-mediated post-transcriptional gene silencing. Furthermore, for specific and effective detection of PLDMV, one hybridoma cell line 145G4B11 secreted monoclonal antibody (MAb) to PLDMV CP was selected by immunizing mice with pET-32a(+) expressed antigen from E. coli. The titer of ascitic fluid of this MAb (145G4B11) to PLDMV CP was 64,000 as determined by indirect ELISA. In western blotting, 145G4B11 was more specific to PLDMV CP than As59, a polyclonal antibody against PLDMV. In summary, our R0 and R1 transgenic lines with double resistance are considered having a great potential to control both PRSV and PLDMV. In addition, the MAb produced 145G4B11 is an efficient serological tool for detection of PLDMV in diseased samples from field.

碩士
國立中興大學
植物病理學系
84
Papaya ringspot virus (PRSV), a member of the Potyvirus genus, contains two major groups, type P ( PRSV P) and type W (PRSV W) virus. The host range of PRSV W strains is limited to Chenopodiaceae and Cucurbitaceae, whereas P type strains infect Cariceae (papaya) in addition. In order to develop transgenic cucurbits with resistance to PRSV W in Taiwan, typical PRSV W isolates from the island were collected and the variability in the nucleotide and amino acid sequences of the CP genes were analyzed. Twelve isolates from the forty ELISA positive samples, collected from six cucurbit crops from different areas of Taiwan, were identified by host reactions and serology tests as typical W type virus isolates. They did not infect papaya but were serologically indistinguishable from type P isolates when tested against the antisera to PRSV P type or PRSV W type. In order to analyze the polymorphisms of the CP genes of the 12 PRSV W type isolates from Taiwan and other reported PRSV W and P type viruses, digestion patterns of RT-PCR products,which were amplified from the N-terminal half of the CP genes, with RsaI, AluI and NlaIII were compared. The results showed that most of the 12 PRSV W isolates from Taiwan were closely related to PRSV P- YK, a P type strain from Taiwan, and P-PD, a P type strain from Thailand,and far apart from P-HA, a P type strain from Hawaii, and W-FL, a W type strain from Florida. To further analyze the variation of the CP genes of PRSV W isolates from Taiwan, three isolates, PRSV W-CI (from Chiayi), W-TN (from Tainan) and W-PT ( from Pingtung), were chosen for cDNA cloning for determination of their CP gene sequences. Comparison the three isolates of Taiwan with each other, indicated that they shared 96.37-96.99% and 94.46-96.74% nucleotide and amino acid identity, respectively, and the nucleotide identity of the 3' non-coding regions were 98.56-99.04%, indicating that the three isolates were closely related strains of the same virus. Comparison of the three W isolates from Taiwan with other reported W isolates of W-FL (from Florida) and W-AU (from Australia), and P isolates of P- YK (from Yung Kang, Taiwan), P-HA (from Hawaii), and P-FL (from Florida) revealed that the nucleotide identity of the CP genes of the three W type isolates from Taiwan shared higher percentages of 95.93-96.64% with P-YK, another P type isolate from Taiwan, they shared lower percentages of 90.59-91.97% with other non-Taiwan PRSV W and P type isolates. In terms of amino acid identity of the CP genes, the three PRSV W type isolates from Taiwan, shared 95.21-96.16% with PRSV P- YK. The comparison of non-Taiwan W and P type isolates showed that they had 95.12-99.3% amino acid identity. The comparison of the 3' non-coding regions of the eight PRSV isolates, revealed that the three PRSV W isolates from Taiwan shared 97.21-98.08% nucleotide identity with P-YK, whereas they shared only 88.51-93.3% nucleotide identity with other non-Taiwan PRSV P and W isolates. The sequences analyses indicated that the relationships among these W and P type isolates could be divided into two groups, one contained PRSV W-CI, W-TN, W-PT and P-YK, the other one contained PRSV W-AU, W-FL, P-HA and P-FL. These coupled with enzyme-digestion polymorphisms indicated that the CP genes of the three W type isolates from Taiwan were closely related to P-YK(a Taiwan isolate) and far apart from W and P type isolates in other different geographic areas. Our results also implicate that degrees of variation of the CP genes do not follow major differences in host specificity, such as papaya or non-papaya infecting, but are more closely corresponding to geographic distribution.

碩士
國立臺灣大學
植物病理與微生物學研究所
103
Papaya ring spot caused by Papaya ring spot virus (PRSV) , one of the most destructive diseases in papaya. PRSV belonging to the genus Potyvirus, family Potyviridae. PRSV-infected papaya trees show mosaic, distorted and shoestring-like symptoms on the leaves, and sunken ring spots on the fruits. PRSV categorized into 2 types, PRSV-P type and PRSV-W type. The P type infects both papayas and cucurbits whereas the W type only infects cucurbits. Based on the incited symptoms, the PRSV-P type further devided into SM (severe mottling), SMN (severe mottling with necrosis) and DF (deformation) strains. Between these 3 strains have apparently differences on pathological and molecular. This study investigate the genomic variations and find the key genomic areas associated with pathogenicity among different PRSV strains through the research with artificially recombinant infectious clones infecting papaya hosts. Based on the previously constructed infectious clones of PRSV SMN and DF strains, two new recombinant infectious named 5’-DF(P1)-SMN and 5’-SMN(P1)-DF clones were further made. The 5’-DF(P1)-SMN clone has a head of DF (5’UTR and P1 fragment of DF) followed by the SMN fragment, and the 5’-SMN(P1)-DF clone has a head of SMN (5’UTR and P1 fragment of SMN) followed by the DF fragment. The recombinant genomic RNA trascripts were synthesized through in vitro transcription, and they were used to individually inoculate the TN2 papayas. The results showed that symptom express of both two recombinant clones similar to PRSV-DF. It revealed that P1 gene contribute part of pathogenicity, but not the only one gene affect symptom express.

This chapter examines the controversies that surround the introduction of transgenic papaya on Hawaii Island, in the wake of the devastation caused by the ring spot virus in the 1990s. It critically examines the respective positions of industry proponents and anti-GM activists, and cautions against the tendency of essentializing GM papayas as either a savior or harbinger of destruction. While both positions raise valid underlying concerns, they both tend to overlook the more difficult challenges of managing smallholder papaya industry in a global market. On the one hand, the benefits and costs of GM papayas are unevenly distributed. On the other hand, he sees a problem in anti-GMO activists’ push for “pure” agriculture, pointing out that the line between “pure” and “impure” and “natural” and “unnatural” are always ambiguous.

The coordination and regulation of growth and development in multicellular organisms is dependent, in part, on the controlled short and long-distance transport of signaling molecule: In plants, symplastic communication is provided by trans-wall co-axial membranous tunnels termed plasmodesmata (Pd). Plant viruses spread cell-to-cell by altering Pd. This movement scenario necessitates a targeting mechanism that delivers the virus to a Pd and a transport mechanism to move the virion or viral nucleic acid through the Pd channel. The identity of host proteins with which MP interacts, the mechanism of the targeting of the MP to the Pd and biochemical information on how Pd are alter are questions which have been dealt with during this BARD project. The research objectives of the two labs were to continue their biochemical, cellular and molecular studies of Pd composition and function by employing infectious modified clones of TMV in which MP is fused with GFP. We examined Pd composition, and studied the intra- and intercellular targeting mechanism of MP during the infection cycle. Most of the goals we set for ourselves were met. The Israeli PI and collaborators (Oparka et al., 1999) demonstrated that Pd permeability is under developmental control, that Pd in sink tissues indiscriminately traffic proteins of sizes of up to 50 kDa and that during the sink to source transition there is a substantial decrease in Pd permeability. It was shown that companion cells in source phloem tissue export proteins which traffic in phloem and which unload in sink tissue and move cell to cell. The TAU group employing MP:GFP as a fluorescence probe for optimized the procedure for Pd isolation. At least two proteins kinases found to be associated with Pd isolated from source leaves of N. benthamiana, one being a calcium dependent protein kinase. A number of proteins were microsequenced and identified. Polyclonal antibodies were generated against proteins in a purified Pd fraction. A T-7 phage display library was created and used to "biopan" for Pd genes using these antibodies. Selected isolates are being sequenced. The TAU group also examined whether the subcellular targeting of MP:GFP was dependent on processes that occurred only in the presence of the virus or whether targeting was a property indigenous to MP. Mutant non-functional movement proteins were also employed to study partial reactions. Subcellular targeting and movement were shown to be properties indigenous to MP and that these processes do not require other viral elements. The data also suggest post-translational modification of MP is required before the MP can move cell to cell. The USA group monitored the development of the infection and local movement of TMV in N. benthamiana, using viral constructs expressing GFP either fused to the MP of TMV or expressing GFP as a free protein. The fusion protein and/or the free GFP were expressed from either the movement protein subgenomic promoter or from the subgenomic promoter of the coat protein. Observations supported the hypothesis that expression from the cp sgp is regulated differently than expression from the mp sgp (Szecsi et al., 1999). Using immunocytochemistry and electron microscopy, it was determined that paired wall-appressed bodies behind the leading edge of the fluorescent ring induced by TMV-(mp)-MP:GFP contain MP:GFP and the viral replicase. These data suggest that viral spread may be a consequence of the replication process. Observation point out that expression of proteins from the mp sgp is temporary regulated, and degradation of the proteins occurs rapidly or more slowly, depending on protein stability. It is suggested that the MP contains an external degradation signal that contributes to rapid degradation of the protein even if expressed from the constitutive cp sgp. Experiments conducted to determine whether the degradation of GFP and MP:GFP was regulated at the protein or RNA level, indicated that regulation was at the protein level. RNA accumulation in infected protoplast was not always in correlation with protein accumulation, indicating that other mechanisms together with RNA production determine the final intensity and stability of the fluorescent proteins.