Abstract
The RNA genome of a resistance-breaking isolate of Lettuce mosaic virus (LMV-E) was engineered to express the jellyfish green fluorescent protein (GFP) or beta-glucuronidase (GUS) fused to the helper-component proteinase (HC-Pro) to study LMV invasion and spread in susceptible and resistant lettuce cultivars. Virus accumulation and movement were monitored by either histochemical GUS assays or detection of GFP fluorescence under UV light. The GFP- and GUS-tagged viruses spread systemically in the susceptible lettuce cultivars Trocadero and Vanguard, where they induced attenuated symptoms, compared with the wild-type virus. Accumulation of the GFP-tagged virus was reduced but less affected than in the case of the GUS-tagged virus. Systemic movement of both recombinant viruses was very severely affected in Vanguard 75, a lettuce cultivar nearly isogenic to Vanguard but carrying the resistance gene mo1(2). Accumulation of the recombinant viruses in systemically infected leaves was either undetectable (GUS-tag) or erratic, strongly delayed, and inhibited by as much as 90% (GFP-tag). As a consequence, and contrary to the parental virus, the recombinant viruses were not able to overcome the protection afforded by the mo1(2) gene. Taken together, these results indicate that GUS or GFP tagging of the HC-Pro of LMV has significant negative effects on the biology of the virus, abolishing its resistance-breaking properties and reducing its pathogenicity in susceptible cultivars.
Highlights
Lettuce mosaic virus (LMV) is one of the most destructive viruses in lettuce and endive crops all over the world (Dinant and Lot 1992)
With an infectious construct in which the full-length cDNA of Lettuce mosaic virus resistance-breaking isolate (LMV-E) is under the control of an enhanced 35S promoter and of the NOS terminator (Yang et al 1998), the marker genes were cloned in a suitable AatII restriction site corresponding to the second and third amino acids of the LMV HCPro
Upon sap inoculation of healthy plants by the viruses derived from plasmid-inoculated plants, the timing of the systemic infection process was found to be the same for LMV-E and LMV-E-green fluorescent protein (GFP), whereas a 2-day delay was generally observed in the case of LMV-E-GUS
Summary
Lettuce mosaic virus (LMV) is one of the most destructive viruses in lettuce and endive crops all over the world (Dinant and Lot 1992). GFP has the advantage of being strongly fluorescent, requiring no substrates or cofactors to form the fluorescent molecule (Chalfie et al 1994) and having proved to be an appropriate, nondestructive technique for the study of the spread of plant viruses during the process of infection (Oparka et al 1997). Through the use of the reporter-tagged potyvirus Tobacco etch virus (TEV-GUS), the major steps in infection have been compared in resistant and susceptible tobacco plants (Schaad and Carrington 1996). The genome of LMV-E was engineered to express either the GUS protein or the GFP, fused to the virus helper component proteinase (HC-Pro). The results demonstrated that tagging of the HC-Pro with either GUS or GFP significantly affects the accumulation, symptom severity, and resistance-breaking properties of LMV
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
