Open AccessNPR1-Independent Activation of Immediate Early Salicylic Acid-Responsive Genes in Arabidopsis
Author(s) -
Carolina Uquillas,
Ingrid Letelier,
Francisca Blanco,
Xavier Jordana,
Loreto Holuigue
Publication year - 2004
Publication title -
molecular plant-microbe interactions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.565
H-Index - 153
eISSN - 1943-7706
pISSN - 0894-0282
DOI - 10.1094/mpmi.2004.17.1.34
Subject(s) - npr1 , arabidopsis , mutant , gene , salicylic acid , transcription factor , biology , coactivator , microbiology and biotechnology , genetics , natriuretic peptide , medicine , heart failure
Salicylic acid (SA) is a key signal for the activation of defense genes in response to stress. The activation of late defense genes by SA, such as PR-1, involves the participation of the NPR1 protein. This protein acts as coactivator of the TGA factors that recognize as-1-like elements in the PR-1 promoter. Considering that functional as-1-like elements are also found in the promoter of SA- and auxin-responsive immediate early genes, we tested the hypothesis that NPR1 is also required for activation of these genes. The expression of the immediate early genes glutathione S-transferase (GST6) and glucosyltransferase (EIGT) was studied in npr1 mutant and wild-type Arabidopsis plants. In the npr1 mutant background, SA and 2,4-dichlorophen-oxyacetic acid were unable to promote transcription of PR-1 but effectively stimulated the expression of GST6 and EIGT. Furthermore, increased binding of proteins to the GST6 as-1-like promoter element was detected in nuclear extracts from npr1 and wild-type plants after treatment with SA. In summary, these results indicate that activation of immediate early genes by SA proceeds through an NPR1-independent pathway. Therefore, we propose that activation by SA of immediate early and late genes occur by different mechanisms.