Susceptibility of transgenic tobacco plants expressing tobacco rattle virus coat protein to nematode-transmitted and mechanically inoculated tobacco rattle virus

Abstract

Transgenic Samsun NN tobacco plants expressing the coat protein of tobacco rattle virus were exposed to mechanical leaf inoculation with tobacco rattle virus and to viruliferous trichodorid vector nematodes. Whereas plants were resistant to mechanical inoculation the vector nematodes successfully transmitted tobacco rattle virus to the roots as well as to the leaves of these plants.It is suggested that transgenic resistance is overcome either because vector nematodes inject relatively large numbers of virus particles into a cell or because they inject destabilized particles. The results indicate that coat protein-mediated resistance is unlikely to be of value for controlling tobacco rattle virus in field crops.

Resistance of transgenic tobacco plants incorporating the putative 57-kDa polymerase read-through gene of Tobacco rattle virus against rub-inoculated and nematode-transmitted virus

“…Root-inoculation of 81G plants by nematodes carrying TRV-GR resulted in resistance characteristics similar to leaf rub-inoculation, with younger plants at the second leaf stage being susceptible but more mature plants exhibiting resistance. Resistance of line 81G against nematode transmitted TRV-PpK20 was displayed as total absence of virus infection in the foliar part of the plants, in strong contrast to previous studies where tobacco plants expressing the TRV CP or potato plants incorporating the replicase 57K domain were infected after inoculation by viruliferous nematodes (Ploeg et al 1993;Melander 2006).…”

“…Pathogen-derived resistance against TRV has been attempted in numerous previous studies using various constructs for plant transformation. Thus, tobacco plants transformed with the CP genes of isolates PLB and TCM exhibited resistance only against inoculation with virions of the homologous isolate, and not against RNA inocula (Van Dun and Bol 1988;Angenent et al 1990) nor, most importantly, against virus transmitted by nematodes (Ploeg et al 1993). No resistance was observed in plants transformed with the genes for the nonstructural 1a and 1b proteins, sequences, respectively; pNOS, nopaline synthase gene promoter sequences; nptII, neomycin phosphotransferase gene; tNOS, nopaline synthase gene terminator sequences; CaMV 35S, Cauliflower mosaic virus 35S promoter sequences derived from RNA1 of isolate PLB, or in plants transformed with the gene for a nonstructural nematode transmission protein (protein 2b) from RNA2 of isolate TCM (Angenent et al 1990).…”

Transgenic Resistance

“…Translatable/ antisense Hackland, Coetzer, Rybicki, and Thomson (2000) Continued (1988) Translatable Angenent, van den Ouweland, and Bol (1990) Translatable Ploeg, Mathis, Bol, Brown, and Robinson (1993) Tobacco ringspot virus (TRSV) Translatable Zadeh and Foster (2004) Tobacco streak virus (TSV)…”

Resistance to plant viruses: Obtaining genes by non-conventional approaches

“…There are at least two examples of transgenic lines which showed protection on mechanical inoculation but not on transmission by vectors . One line of potatoes expressing potato virus Y coat protein was not protected against aphid inoculation (Lawson et al, 1990) and transgenic tobacco plants expressing tobacco rattle virus coat protein were not protected against nematode transmission (Ploeg et al ., 1993) .…”