| Citrus tristeza virus (CTV) is distributed worldwide and is the most devastating viral citrus disease. The objectives of this study were to obtain transgenic citrus plants and to evaluate the cross protecting ability of transgenic sour orange citrus plants expressing the coat protein of the CTV when challenged with the severe strain T-36. It has been demonstrated that transgenic plants expressing a plant virus coat protein (CP) can be resistant to infection by the homologous virus. Powell-Abel and collaborators were the first to demonstrate that transgenic tobacco expressing the coat protein gene of tobacco mosaic virus (TMV) was resistant to TMV infection. Many other reports have since shown that this phenomenon, referred to as pathogen-derived resistance by some and as coat protein-mediated protection (CPMP) by others, is broadly applicable to different groups of plant viruses. Importantly, this phenomenon has obvious applications to plant protection because it provides a direct approach for incorporating resistance into commercially acceptable cultivars or breeding lines. We have produced transgenic citrus plants that express the CP gene from CTV strain T36 using an Agrobacterium-mediated method. The effects of Agrobacterium strain/vector plasmid combinations, hormone concentration, and citrus genotype on the frequency of transgenic plant production were investigated. The greatest improvement in transformation frequency (... |
