期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2002
卷号：99
期号：6
页码：3645-3650
DOI：10.1073/pnas.062041499
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Expression of tobacco mosaic virus (TMV) coat protein (CP) in plants confers resistance to infection by TMV and related tobamoviruses. Certain mutants of the CP (CPT42W) provide much greater levels of resistance than wild-type (wt) CP. In the present work, infection induced by RNA transcripts of TMV clones that contain wt CP or mutant CPT42W fused to the green fluorescent protein (GFP) (TMV-CP:GFP, TMV-CPT42W:GFP) and clones harboring TMV movement protein (MP):GFP were followed in nontransgenic and transgenic tobacco BY-2 protoplasts and Nicotiana tabaccum Xanthi-nn plants that express wt CP or CPT42W. On nontransgenic and wt CP transgenic plants, TMV-CP:GFP produced expanding, highly fluorescent disk-shaped areas. On plants expressing CPT42W, infection by TMV-CP:GFP or TMV-MP:GFP-CP produced infection sites of smaller size that were characterized by low fluorescence, reflecting reduced levels of virus spread and reduced accumulation of both CP:GFP and MP:GFP. TMV-CPT42W:GFP failed to produce visible infection sites on nontransgenic plants, yet produced normal infection sites on MP-transgenic plants that produce MP. TMV infection of transgenic BY-CPT42W protoplasts resulted in very low levels of MP accumulation, whereas on BY-CP protoplasts (containing wt CP), infection produced higher levels of MP than in nontransgenic BY-2 cells. The results suggest that wt CP has a positive effect on the production of MP, whereas the CPT42W has a negative effect on MP accumulation and/or function. This effect results in very high levels of resistance to TMV infection in plants containing CPT42W. This report shows that the CP of a plant virus regulates production of the MP, and that a mutant CP interferes with MP accumulation and cell-to-cell movement of infection.
