Strategies for antiviral resistance in transgenic plants. Mol Plant Pathol 9:73-83

Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD, Wageningen, The Netherlands.
Molecular Plant Pathology (Impact Factor: 4.72). 02/2008; 9(1):73-83. DOI: 10.1111/j.1364-3703.2007.00447.x
Source: PubMed


Genetic engineering offers a means of incorporating new virus resistance traits into existing desirable plant cultivars. The initial attempts to create transgenes conferring virus resistance were based on the pathogen-derived resistance concept. The expression of the viral coat protein gene in transgenic plants was shown to induce protective effects similar to classical cross protection, and was therefore distinguished as 'coat-protein-mediated' protection. Since then, a large variety of viral sequences encoding structural and non-structural proteins were shown to confer resistance. Subsequently, non-coding viral RNA was shown to be a potential trigger for virus resistance in transgenic plants, which led to the discovery of a novel innate resistance in plants, RNA silencing. Apart from the majority of pathogen-derived resistance strategies, alternative strategies involving virus-specific antibodies have been successfully applied. In a separate section, efforts to combat viroids in transgenic plants are highlighted. In a final summarizing section, the potential risks involved in the introduction of transgenic crops and the specifics of the approaches used will be discussed.

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    • "In the past few decades, many transgenic plants have been developed with resistance against bacteria, viruses, and viroids (Fitchen and Beachy 1993;Ishida et al. 2002;Prins et al. 2008). Specifically, transgenic plants expressing recombinant dsRNA-specific RNases display a broad spectrum resistance to a variety of plant RNA viruses and viroids (Fitchen and Beachy 1993;Prins et al. 2008;Sano et al. 1997). Some companies have developed transgenic plants tolerant to herbicide and harmful insect (Prado et al. 2014). "
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    ABSTRACT: Chrysanthemum stunt viroid (CSVd), the smallest plant pathogen known to infect chrysanthemums, is a single-stranded circular RNA viroid that induces stunting that results in an overall height reduction of 30–50 % in mature plants. A catalytic single-chain variable antibody, 3D8 scFv, which exhibits intrinsic DNase and RNase activities, was expressed in chrysanthemums to generate transgenic plant resistance to CSVd infection. Moreover, a codon-optimized version of the 3D8 scFv gene for chrysanthemums was also transformed into plants; these codon-optimized transgenic chrysanthemums expressed twice as much 3D8 scFv and displayed 60 % more resistance to CSVd infection, compared with transgenic chrysanthemums harboring the original 3D8 scFv gene. CSVd challenge experiments with codon-optimized and original 3D8 scFv-transgenic chrysanthemums showed that CSVd in newly produced leaves of both codon-optimized and original 3D8 scFv-transgenic plants was not detected by RT-PCR. This is the first report describing the development of a CSVd-resistant chrysanthemum harboring a catalytic single-chain antibody, 3D8 scFv, which has intrinsic RNase activity.
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    • "Infiltration of Nicotiana benthamiana leaves with RNAi constructs derived from the genome of either Pepper golden mosaic virus or Tomato chino La Paz virus partly suppressed disease symptoms (Medina-Hernandez et al. 2013). An RNAi approach using the V1 open reading frame (ORF) of begomovirus resulted, in some cases, in broad protection against multiple monopartite begomovirus strains (reviewed by Prins et al. 2008), but simultaneous RNAi mediated resistance against monopartite and bi-partite tomato-infecting begomoviruses has not been shown previously. Here we report the identification of regions of the monopartite genome of ToLCTWV for RNAi approaches to suppress disease symptoms and accumulation of the virus, and the subsequent exploration of the capability of fusion constructs that contain homologous regions of both ToLCTWV and TYLCTHV in RNAi experiments to protect tomato against both virus species. "
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    ABSTRACT: Tomato yellow leaf curl disease caused by different begomovirus species leads to substantial tomato production losses worldwide. In Taiwan, the monopartite tomato leaf curl Taiwan virus (ToLCTWV) and bi-partite tomato yellow leaf curl Thailand virus (TYLCTHV) are the predominant begomovirus species causing this disease. Resistance genes are available in wild tomato species and a continuous search for new resistance genes and alternative control methods is required to respond to the rapid evolution of virus strains. RNA interference is an efficient technology to induce resistance against viral pathogens. Six different sections of the ToLCTWV genome were tested in transformed tomato for their capacity to reduce symptoms and inhibit viral DNA accumulation. The two most effective constructs for ToLCTWV infection carried regions of the C1 and C2 genes, and portions of either the C3 or C4 gene of ToLCTWV. A RNAi construct containing fusions of C1, C2 and C3 sections of ToLCTWV and the corresponding sections of the TYLCTHV DNA-A genome were introgressed into tomato line CLN1621L. R1 and R2 families were challenged using viruliferous whiteflies in separate screen houses for ToLCTWV and TYLCTHV. Sixteen and 12 R2 plants derived from one primary transformant remained symptomless until at least 3 weeks after exposure to ToLCTWV and TYLCTHV, respectively, and accumulated only very low titres of viral DNA, as shown by real-time polymerase chain reaction analysis. Our results suggest that expression of bi-viral RNAi constructs in tomato can lead to resistance against two different tomato infecting begomovirus species.
    No preview · Article · Sep 2015 · Journal of Plant Biochemistry and Biotechnology
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    • "The age of the plants is also an important variable related to the disease, since some genotypes present different responses (susceptibility or resistance) when they are inoculated in seedling stages or when they are adult plants (Leão et al. 2006; Pinto et al. 2008). Fig. 6 Ratings of the severity of symptoms incited by CABMV in three UENFH-9 progeny genotypes based on scores weekly recorded between August and December 2012 Eur J Plant Pathol The posttranscriptional gene silencing (PTGS) mechanism or RNA silencing is another factor that may explain the disease symptom regression on hybrid genotypes over time (Prins et al. 2008). The observation that plants which have recovered from a first viral infection become resistant to reinfection with the same virus due to silencing activation and conservation, led to the hypothesis that RNA silencing would be an adaptive defense response to the virus (Al-Kaff et al. 1998). "
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    ABSTRACT: The potyvirus-induced passion fruit woodiness disease (PWD) is considered the most important limiting factor for passion fruit production in several countries. In Brazil, PWD is caused by the Cowpea aphid-borne mosaic virus (CABMV), and to date there are no reports on the existence of P. edulis genotypes resistant to this virus. Thus, resistance gene introgression from wild Passiflora species for a commercial species, via interspecific hybridization, is one of the strategies adopted in order to control the disease. The current study’s goals were to: confirm CABMV occurrence under field conditions; assess the resistance to CABMV in 178 Passiflora genotypes constituted by interspecific hybrids and their parents (P. edulis and P. setacea), as well as to estimate genetic parameters for the area under the disease progress curve (AUDPC), in order to obtain cultivars of sour passion fruit resistant to CABMV in future. The experimental design was set according to unbalanced randomized blocks with two repetitions. Data referring to the AUDPC were analyzed by means of the mixed models methodology (REMI/BLUP). CABMV infections were confirmed in sour passion fruit plants and in interspecific hybrids by observing foliar mosaic symptoms and by PTA-ELISA with specific antiserum against CABMV. There was a difference on the intensity of symptoms induced by CABMV for the 178 Passiflora genotypes assessed under natural occurrence conditions. The higher AUDPC values were obtained for 41 hybrids and for all P. edulis genotypes. In turn, lower values were estimated for 115 hybrid genotypes and for all P. setacea individuals. Of the 31 genotypes assessed by PTA-ELISA, 28 were considered resistant, out of those three P. setacea genotypes and 25 hybrids. Estimated AUDPC heritability values (0.99) and accuracy (0.99) enable inferring that resistance to CABMV within the assessed population was highly inheritable, allowing high selective efficiency. Resistant hybrid plants will be able to be selected and recombined with P. edulis genotypes and, again, assessed in order to corroborate the resistance to the virus, providing means of following up with the breeding genetic program on CABMV resistance.
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