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United States Department of Agriculture

Agricultural Research Service

Title: The Helicase Domain of the Tmv Replicase Proteins Induces the N-Mediated Defence Response in Tobacco

Authors
item Erickson, F. Les - UCB/ARS PGEC ALBANY CA
item Holzberg, Steve - UCB ESP&M BERKELEY
item Calderon-Urrea, Alejandro - UCB/ARS PGEC ALBANY CA
item Handley, Vanessa - UCB/ARS PGEC ALBANY CA
item Axtell, Michael - UCB P&MB BERKELEY
item Corr, Catherine - UCB/ARS PGEC ALBANY CA
item Baker, Barbara

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1999
Publication Date: April 1, 1999
Citation: Erickson, F., Holzberg, S., Calderon-Urrea, A., Handley, V., Axtell, M., Corr, C., Baker, B.J. 1999. The helicase domain of the TMV replicase proteins induces the N-mediated defence response in tobacco. Plant Journal 18(1) 67-75.

Interpretive Summary: Tobacco mosaic virus (TMV) induces the hypersensitive response (HR) in tobacco plants containing the N gene. This defence response is characterized by cell death at the site of virus infection and inhibition of viral replication and movement. We demonstrate that recombinant p50 protein has ATPase activity, as suggested by the presence of conserved sequence motifs found in ATPase/helicase enzymes. A point mutation that alters one of these motifs abolishes ATPase activity invitro but does not affect HR induction. These results suggest that features of the TMV helicase domain, independent of its enzymatic activity, are recognized by N-containing tobacco to induce TMV resistance.

Technical Abstract: Tobacco mosaic virus (TMV) induces the hypersensitive response (HR) in tobacco plants containing the N gene. This defence response is characterized by cell death at the site of virus infection and inhibition of viral replication and movement. A previous study indicated that a portion of the TMV replicase containing a putative helicase domain is involved in HR induction. Here, this observation is confirmed and extended by showing that non-viral expression of a 50 kDa TMV helicase fragment (p50) is sufficient to induce the N-mediated HR in tobacco. Like the HR elicited by TMV infection, transgenic expression of p50 induces a temperature-sensitive defence response. We demonstrate that recombinant p50 protein has ATPase activity, as suggested by the presence of conserved sequence motifs found in ATPase/helicase enzymes. A point mutation that alters one of these motifs abolishes ATPase activity invitro but does not affect HR induction. These results suggest that features of the TMV helicase domain, independent of its enzymatic activity, are recognized by N-containing tobacco to induce TMV resistance.

Last Modified: 10/1/2014
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