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The Arabidopsis homeobox gene ATHB‐7 is induced by water deficit and by abscisic acid
Author(s) -
Söderman Eva,
Mattsson Jim,
Engström Peter
Publication year - 1996
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1996.10020375.x
Subject(s) - abscisic acid , mutant , arabidopsis , homeobox , biology , wild type , gene , arabidopsis thaliana , microbiology and biotechnology , transcription factor , gene expression , biochemistry
Homeodomain‐leucine zipper (HD‐Zip) proteins are putative transcription factors encoded by a class of recently discovered homeobox genes as yet found only in plants. This paper reports on the characterization of one of these genes, ATHB‐7 , in Arabidopsis thaliana . ATHB‐7 transcripts were present in all organs of the plant at low levels, but expression was induced several‐fold by water deficit, osmotic stress as well as by exogenous treatment with abscisic acid (ABA), a response being detectable at 10 −8 M and reaching a maximum at 10 −6 M ABA. The ATHB‐7 transcript was detected within 30 min after treatment with ABA and the transcript level was rapidly reduced after removal of the hormone. The induction of ATHB‐7 was shown to be mediated strictly via ABA, since no induction of ATHB‐7 was detectable in the ABA‐deficient mutant aba‐3 subjected to drought treatment. Induction levels in two ABA‐insensitive mutants abi2 and abi3 were similar to the wild‐type response. In the abi1 mutant, however, induction was impaired as 100‐fold higher concentrations of ABA were required for a maximum induction as compared with wild‐type. In this mutant the ATHB‐7 response was reduced also after drought and osmotic stress treatments. These results indicate that ATHB‐7 is transcriptionally regulated in an ABA‐dependent manner and may act in a signal transduction pathway which mediates a drought response and also includes ABI1.