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United States Department of Agriculture

Agricultural Research Service

Title: Interactions Between Tobacco Mosaic Virus and the Tobacco N Gene

Authors
item Baker, Barbara
item Erickson, F. - UCB-PGEC
item Dinesh-Kumar, S. - UCB-PGEC
item Holzberg, S. - UCB-PGEC
item Ustach, C. - UCB-PGEC
item Dutton, M. - UCB-PGEC
item Handley, V. - UCB-PGEC
item Corr, C. - UCB-PGEC

Submitted to: Proceedings of the Royal Society of London B
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 1999
Publication Date: March 1, 1999
Citation: Baker, B.J., Erickson, F.L., Dinesh-Kumar, S.P., Holzberg, S., Ustach, C., Dutton, M., Handley, V., Corr, C. 1999. Interactions between tobacco mosaic virus and the tobacco N gene. Proceedings of the Royal Society of London B., 354(1383):653-658.

Interpretive Summary: The interaction between tobacco mosaic virus (TMV) and tobacco harbouring the N gene is a classical system for studying gene-for-gene interactions in disease resistance. As a result of our investigation, both components of this gene-for-gene interaction are now available for studies that address the molecular mechanisms involved in N-mediated TMV resistance.

Technical Abstract: The interaction between tobacco mosaic virus (TMV) and tobacco harbouring the N gene is a classical system for studying gene-for-gene interactions in disease resistance. The N gene confers resistance to TMV by mediating defence responses that function to limit viral replication and movement. We isolated the N gene and determined that N belongs to the nucleotide-binding-site-leucine-rich-repeat (NBS-LRR) class of plant disease resistance genes, and encodes both full-length and truncated proteins. Sequence homologies and mutagenesis studies indicated a signalling role for the N protein similar to that seen for proteins involved in defence responses in insects and mammals. The N gene confers resistance to TMV in transgenic tomato, demonstrating the use of the NBS-LRR class of disease resistance genes in engineering crop resistance. From the pathogen side of this interaction, the TMV 126 kDa replicase protein has been implicated as the avirulence factor that triggers N-mediated defence responses. We employed Agrobacterium-mediated expression strategies to demonstrate that expression of the putative helicase region of the replicase protein is sufficient to elicit N-mediated defences. The thermosensitivity of the N-mediated response to TMV is retained when induced by expression of this replicase fragment. Thus, both components of this gene-for-gene interaction are now available for studies that address the molecular mechanisms involved in N-mediated TMV resistance.

Last Modified: 10/24/2014
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