Accumulation of the two transcripts of the N gene, conferring resistance to tobacco mosaic virus, is probably important for N gene-dependent hypersensitive cell death.
The N gene is a Toll/interleukin-1 receptor (TIR)-nucleotide-binding site (NBS)-leucine-rich repeat (LRR)-type resistance (R) gene that generates two alternative transcripts, N(S) and N(L). N(S) encodes the full-length N protein while N(L) is predicted to encode a truncated form of the protein lacking most of the LRR region. We found that the two transcripts were accumulated at 20 degrees C, a permissive temperature, but not at 30 degrees C, a non-permissive temperature for the N gene, in tobacco mosaic virus (TMV)-inoculated leaves. When N gene-dependent cell death was triggered by transient 20 degrees C treatment for 2-6 h, considerable levels of the transcripts were accumulated just before cell death, although the levels of N(S) were always higher. The accumulation was induced by transient expression of the 50 kDa helicase domain (p50) of TMV replicase which is the Avr component of N, but not by transient expression of NtMEK2 (DD)-mediated cell death or N gene-independent hypersensitive cell death. These results suggest that the accumulation of N(S) and N(L) is associated with the function of N and, above a certain threshold, triggers N-mediated hypersensitive cell death.
Takabatake
Reona
R
National Institute of Agrobiological Sciences (NIAS), Kannon-dai, Tsukuba, Ibaraki, 305-8602 Japan.
Seo
Shigemi
S
Mitsuhara
Ichiro
I
Tsuda
Shinnya
S
Ohashi
Yuko
Y
D016923:Cell Death; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007113:Immunity, Innate; D048370:MAP Kinase Kinase 2 / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000821:virology*; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013696:Temperature; D014026:Nicotiana / Q000166:cytology / Q000235:genetics* / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000502:physiology*; D051193:Toll-Like Receptors / Q000235:genetics / Q000502:physiology; D014158:Transcription, Genetic
C089425:N protein, Nicotiana glutinosa; D010940:Plant Proteins; D051193:Toll-Like Receptors; D048370:MAP Kinase Kinase 2; C085103:tobacco mosaic virus replicase; D012324:RNA-Dependent RNA Polymerase