A Tobamovirus Causing Heavy Losses in Protected Pepper Crops in Spain
TL;DR: During a four-year survey of plant viruses infecting pepper cultivars grown under plastic in the Southeastern region of Spain, a tobamovirus was found to be the major disease agent of this crop, causing a catastrophic disease.
Abstract: During a four-year (1982–1985) survey of plant viruses infecting pepper cultivars grown under plastic in the Southeastern region of Spain, a tobamovirus was found to be the major disease agent of this crop. The virus produces slight or no symptoms on the leaves, but causes chlorotic mottling, malformation and reduction in size with occasional necrosis on the fruits and was able to infect all commercial pepper cultivars tested, including those resistant to other tobamoviruses, causing a catastrophic disease. The biological and serological characterization of the virus showed that it is very similar to pepper mild mottle virus (PMMV) (Wetteret al. 1984) and therefore we have termed it as Spanish strain of PMMV (PMMV-S). The need of grouping all the so-called “pepper strains” of tobacco mosaic virus (TMV) as a new distinct member of the tobamovirus group with the name of PMMV is emphasized.
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TL;DR: The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase, linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin.
Abstract: In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.
450 citations
TL;DR: The in vivo expression system to produce large amounts of virus-derived dsRNAs in bacteria is developed, providing an alternative to genetic transformation of plant species with dsRNA-expressing constructs capable to interfere with plant viruses.
Abstract: Double-stranded RNA (dsRNA) is a potent initiator of gene silencing in a diverse group of organisms that includes plants, Caenorhabditis elegans, Drosophila and mammals. We have previously shown and patented that mechanical inoculation of in vitro-transcribed dsRNA derived from viral sequences specifically prevents virus infection in plants. The approach required the in vitro synthesis of large amounts of RNA involving high cost and considerable labour. We have developed an in vivo expression system to produce large amounts of virus-derived dsRNAs in bacteria, with a view to providing a practical control of virus diseases in plants. Partially purified bacterial dsRNAs promoted specific interference with the infection in plants by two viruses belonging to the tobamovirus and potyvirus groups. Furthermore, we have demonstrated that easy to obtain, crude extracts of bacterially expressed dsRNAs are equally effective protecting plants against virus infections when sprayed onto plant surfaces by a simple procedure. Virus infectivity was significantly abolished when plants were sprayed with French Press lysates several days before virus inoculation. Our approach provides an alternative to genetic transformation of plant species with dsRNA-expressing constructs capable to interfere with plant viruses. The main advantage of this mode of dsRNA production is its simplicity and its extremely low cost compared with the requirements for regenerating transgenic plants. This approach provides a reliable and potential tool, not only for plant protection against virus diseases, but also for the study of gene silencing mechanisms in plant virus infections.
199 citations
Cites methods from "A Tobamovirus Causing Heavy Losses ..."
...Leaf samples were homogenized in ELISA sample buffer at 1 g/ 50 ml, and aliquots of sap (100 μl) transferred to two wells of a microtiter plate coated with polyclonal antibodies against PPV (REALISA-PPV, Durviz) or PMMoV [32]....
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TL;DR: The entire genomic RNA of a Spanish isolate of pepper mild mottle virus (PMMV-S), a resistance-breaking virus in pepper, was cloned and sequenced and shown to be similar to other tobamoviruses in its genomic organization.
Abstract: The entire genomic RNA of a Spanish isolate of pepper mild mottle virus (PMMV-S), a resistance-breaking virus in pepper, was cloned and sequenced and shown to be similar to other tobamoviruses in its genomic organization. It consisted of 6357 nucleotides (nt) and contained four open reading frames (ORFs) which encode a 126K protein and a readthrough 183K protein (nt 70 to 4908), a 28K protein (nt 4909 to 5682) and a 17.5K coat protein (nt 5685 to 6158). This is the first tobamovirus in which none of the ORFs overlap. Both its nucleic acid and predicted protein sequences were compared with the previously determined sequences of other tobamoviruses. The variations and similarities found and their relationship with the pathogenicity of this virus are discussed.
103 citations
TL;DR: The RT- PCR-RFLP using general primers as well as the RT-PCR using species specific primers were proven to be useful for the diagnosis and control of the disease and will be helpful for resistance breeding, epidemiological investigations and plant virus collections.
102 citations
TL;DR: Evidence is presented for a differential accumulation of C. chinense PR proteins and mRNAs in the compatible (PMMoV-I)-C.
Abstract: Resistance conferred by the L(3) gene is active against most of the tobamoviruses, including the Spanish strain (PMMoV-S), a P(1,2) pathotype, but not against certain strains of pepper mild mottle virus (PMMoV), termed P(1,2,3) pathotype, such as the Italian strain (PMMoV-I). Both viruses are nearly identical at their nucleotide sequence level (98%) and were used to challenge Capsicum chinense PI159236 plants harbouring the L(3) gene in order to carry out a comparative proteomic analysis of PR proteins induced in this host in response to infection by either PMMoV-S or PMMoV-I. PMMoV-S induces a hypersensitive reaction (HR) in C. chinense PI159236 plant leaves with the formation of necrotic local lesions and restriction of the virus at the primary infection sites. In this paper, C. chinense PR protein isoforms belonging to the PR-1, beta-1,3-glucanases (PR-2), chitinases (PR-3), osmotin-like protein (PR-5), peroxidases (PR-9), germin-like protein (PR-16), and PRp27 (PR-17) have been identified. Three of these PR protein isoforms were specifically induced during PMMoV-S-activation of C. chinense L(3) gene-mediated resistance: an acidic beta-1,3-glucanase isoform (PR-2) (M(r) 44.6; pI 5.1), an osmotin-like protein (PR-5) (M(r) 26.8; pI 7.5), and a basic PR-1 protein isoform (M(r) 18; pI 9.4-10.0). In addition, evidence is presented for a differential accumulation of C. chinense PR proteins and mRNAs in the compatible (PMMoV-I)-C. chinense and incompatible (PMMoV-S)-C. chinense interactions for proteins belonging to all PR proteins detected. Except for an acidic chitinase (PR-3) (M(r) 30.2; pI 5.0), an earlier and higher accumulation of PR proteins and mRNAs was detected in plants associated with HR induction. Furthermore, the accumulation rates of PR proteins and mRNA did not correlate with maximal accumulation levels of viral RNA, thus indicating that PR protein expression may reflect the physiological status of the plant.
101 citations
Cites background from "A Tobamovirus Causing Heavy Losses ..."
...In this work, a comparative analysis of PR protein accumulation in C. chinense PI159236 plants in response to the infection of the Spanish and Italian strains of pepper mild mottle virus (PMMoV-S and PMMoV-I, respectively) (Wetter et al., 1984; Alonso et al., 1989) is described....
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References
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TL;DR: Experiments reported here support the notion that intact TMV RNA has genes which are not translated directly and that specific fragments of the RNA are the functional messengers for those genes.
190 citations
122 citations
TL;DR: The comparison of the deduced amino acid sequence between the tomato and the common strain shows that the 30K protein is composed of the conserved N-terminal four-fifth and the highly divergent region near the C-terminus.
Abstract: The cDNA copies of tobacco mosaic virus (TMV)-tomato strain (L) genome were cloned by the method of Okayama and Berg (Mol. Cell. Biol. 2, 161-170. (1982)) and the sequence of 1,614 nucleotides at the 3' end was determined. The sequence encompasses the 30K and the coat protein cistron which are located in residues 685-1, 479 and 203-682 from the 3' end of the genome respectively. The close relationship between the tomato and the common strain was shown on the level of the nucleotide sequence. Highly homologous regions are found in the 3' non-coding region, the assembly origin and the 5' flanking region of the 30K protein cistron. The comparison of the deduced amino acid sequence between the tomato and the common strain shows that the 30K protein is composed of the conserved N-terminal four-fifth and the highly divergent region near the C-terminus.
60 citations
TL;DR: It was concluded that similarities of strains in their reactions inCapsicum spp.
Abstract: Using test plants and serology six tobamoviruses of pepper (FO, Ob, P8, P11, P14 and SL) and one of eggplant (A1) were compared with common tobacco mosaic virus (TMV-WU1). WU1, A1 and FO were closely similar in their reactions inCapsicum spp. as were P14 and SL. Ob, P11 and P8 were also similar in this respect except inC. frutescens ‘Tabasco’ in which P8 differed from Ob and P11. Using micro-precipitation tests the virus strains could be roughly divided into three serological groups: Group I consisted of WU1, group II of A1, FO, P8, P14 and SL, and group III of P11 and Ob. With ELISA group II was further divisible into two subgroups, including A1 and FO, and P8, P14 and SL. It was concluded that similarities of strains in their reactions inCapsicum spp., were not necessarily confirmed by their serological relationships. Zes tobamovirussen uit peper (FO, Ob, P8, P11, P14 en SL) en een uit aubergine (A1) konden met behulp van toetsplanten alle van elkaar worden onderscheiden. In hun reacties inCapsicum-soorten, kwamen A1 en FO sterk overeen met elkaar en met het gewone tabaksmozaiekvirus (WU1). Ob, P11 en P8, die in dit opzicht onderling veel overeenkomst vertoonden, verschilden duidelijk van alle andere. Hetzelfde gold voor P14 en SL. Ook met behulp van de micro-precipitatietoets konden de virusstammen in groepen worden ingedeeld. Groep I werd gevormd door WU1, groep II door A1, FO, P8, P14 en SL en groep III door P11 en Ob. Met behulp van ELISA kon groep II worden onderverdeeld in twee ondergroepen, namelijk A1 en FO enerzijds en P8, P14 en SL anderzijds. De nauwe serologische verwantschap van A1 met FO is conform de grote overeenkomst in waardplantreacties. Hetzelfde geldt voor P11 en Ob, wanneer we alleen hun reacties inCapsicum-soorten beschouwen. P8 echter, die wat het laatste betreft meer op Ob en P11 lijkt, vertoonde serologisch meer overeenkomst met P14 en SL. WU1 verschilde serologisch zeer sterk van alle andere onderzochte virusstammen. Geoconcludeerd kan worden dat de waargenomen overeenkomst tussen de onderzochte virusstammen in hun reacties inCapsicum-soorten niet altijd gesteund wordt door hun serologische verwantschappen.
58 citations
TL;DR: The results showed that the internal initiation and the bidirectional elongation are a universal mechanism of assembly among TMV strains, but different strains may use different initiation sites.
51 citations