Induction of a hypersensitive response by chimeric helicase sequences of tobamoviruses U1 and Ob in N-carrying tobacco.
Recently, the helicase domain of the Tobacco mosaic virus (TMV)-U1 replicase proteins (designated MOREHEL:U1) was identified as the elicitor of the N gene-mediated hypersensitive response (HR) in tobacco. In this study, we used agroinfiltration to express the equivalent MOREHEL domain of the non-HR-inducing tobamovirus strain TMV-Ob. It appeared that this MOREHEL:Ob sequence did not elicit a HR in N gene-carrying tobacco. Both MOREHEL sequences were divided into eight subdomains, and chimeras of MOREHEL sequences from U1 and Ob were constructed. Expression of these chimeric MOREHEL sequences revealed that, in the TMV-U1 MOREHEL sequence, at least four domains involved in full HR induction were present. The presence of at least three of these four domains seems a minimal requirement for HR induction. Two additional domains may play a minor role in HR induction. To study the elicitor function of the chimeras during the TMV life cycle, chimeric MOREHEL domains were introduced into full-length TMV cDNA clones. These constructs, however, were unable to establish an infection in Nicotiana benthamiana or Nicotiana tabacum plants.
Abbink
T E
TE
Institute of Molecular Plant Sciences, Gorlaeus Laboratories, Leiden University, The Netherlands.
de Vogel
J
J
Bol
J F
JF
Linthorst
H J
HJ
D000595:Amino Acid Sequence; D001483:Base Sequence; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000235:genetics*; D005814:Genes, Viral; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000201:enzymology* / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics
D018076:DNA, Complementary; D011993:Recombinant Fusion Proteins; C023140:DNA replicase; D004259:DNA-Directed DNA Polymerase; D004265:DNA Helicases