Sp. Dineshkumar et al., TRANSPOSON TAGGING OF TOBACCO MOSAIC-VIRUS RESISTANCE GENE-N - ITS POSSIBLE ROLE IN THE TMV-N-MEDIATED SIGNAL-TRANSDUCTION PATHWAY, Proceedings of the National Academy of Sciences of the United Statesof America, 92(10), 1995, pp. 4175-4180
Plants can recognize and resist invading pathogens by signaling the in
duction of rapid defense responses, Often these responses are mediated
by single dominant resistance genes (R genes), The products of R gene
s have been postulated to recognize the pathogen and trigger rapid hos
t defense responses. Here we describe isolation of the classical resis
tance gene N of tobacco that mediates resistance to the well-character
ized pathogen tobacco mosaic virus (TMV). The N gene was isolated by t
ransposon tagging using the maize Activator (Ac) transposon. We confir
med isolation of the N gene by complementation of the TMV-sensitive ph
enotype with a genomic DNA fragment. Sequence analysis of the N gene s
hows that it encodes a protein,vith an amino-terminal domain similar t
o that of the cytoplasmic domains of the Drosophila Toll protein and t
be interleukin 1 receptor in mammals, a putative nucleotide-binding si
te and 14 imperfect leucine-rich repeats. The presence of these functi
onal domains in the predicted N gene product is consistent with the hy
pothesis that the N resistance gene functions in a signal transduction
pathway. Similarities of N to-Toll and the interleukin 1 receptor sug
gest a similar signaling mechanism leading to rapid gene induction and
TMV resistance.