Strategies for antiviral resistance in transgenic plants

Abstract

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.

Cassava brown streak disease: a threat to food security in Africa

“…In view of the difficulties associated with conventional breeding, genetic engineering offers great potential for the rapid transfer of resistance genes to traditional cultivars, bypassing the possibility of the appearance of undesirable traits. Among the available biotechnological approaches, RNA interference (RNAi) or gene silencing technology, also called post-transcriptional gene silencing, offers significant potential for the control of CBSD Prins et al, 2008;Reddy et al, 2009) (Ezezika et al, 2012;Taylor et al, 2012). Three RNAi constructs targeting different parts of the CP of UCBSV-[UG:Nam:04] were generated, which consisted of the 894 nt (FL, full-length), 397 nt N-terminal (NT) and 491 nt C-terminal (CT) portions of the CP and expressed constitutively in the model host N. benthamiana (Fig.…”

Attenuated plant viruses: preventing virus diseases and understanding the molecular mechanism

“…More recently, transgenic plants with a viral sequence have been proven to confer resistance to the virus from which the transgene was derived or to related viruses (Prins et al 2008). One remarkable example is transgenic papaya; with the coat protein (CP) gene of Papaya ringspot virus (PRSV), it expresses extreme resistance to PRSV (Fuchs and Gonsalves 2008), although the resistance mechanism in this papaya appears to be CP-mediated.…”

Effect of artificial dsRNA on infection of pea plants by Pea seed-borne mosaic virus

“…With recent progress on GMO (transgenic) plants, it has been shown that plant resistance to viral infection can be created in this manner. The molecular breeding process is faster and more genetically controllable (Prins et al 2008). The success of this approach was first demonstrated in tobacco plants, with an inserted gene encoding the TMV coat protein, which showed resistance (Beachy 1999).…”