Open AccessSalicylic acid and the hypersensitive response initiate distinct signal transduction pathways in tobacco that converge on the as‐1 ‐like element of the PR‐1a promoter
Author(s) -
Grüner Rose,
Strompen Georg,
Pfitzner Artur J. P.,
Pfitzner Ursula M.
Publication year - 2003
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1033.2003.03888.x
Subject(s) - reporter gene , response element , cauliflower mosaic virus , promoter , biology , gene , hypersensitive response , signal transduction , gene expression , transgene , transcription (linguistics) , salicylic acid , microbiology and biotechnology , negative regulatory element , regulation of gene expression , transcription factor , gus reporter system , genetically modified crops , genetics , plant disease resistance , linguistics , philosophy
Tobacco pathogenesis‐related protein 1a (PR‐1a) is induced in plants during the hypersensitive response (HR) after exposure of plants to salicylic acid (SA) and by developmental cues. Gene activation by these diverse stimuli is mediated via an as‐1 ‐like element in the PR‐1a upstream region. To further analyze the significance of this cis ‐acting sequence, an authentic as‐1 element from the cauliflower mosaic virus 35S RNA promoter was inserted into the PR‐1a promoter in place of the as‐1 ‐like motif. Reporter gene analysis in transgenic tobacco plants demonstrated that as‐1 can functionally replace the as‐1 ‐like element in the PR‐1a promoter in response to all stimuli. However, reporter gene induction from the as‐1 carrying promoter was enhanced in response to SA compared to the wild‐type promoter, and the ratio of reporter gene activities in SA treated leaf tissue to tissue exhibiting the HR increased with the as‐1 promoter construct. Our findings support a model where PR‐1a gene expression relies on at least two distinct signal transduction pathways initiated by SA and by a yet unknown signal produced during the HR, that promote different, albeit related, transcription complexes on the PR‐1a as‐1 ‐like element. Analysis of PR‐1 proteins in plants expressing salicylate hydroxylase yielded additional evidence that an HR dependent pathway leads to high level PR‐1 gene induction in tobacco.