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Hahb‐4 , a homeobox‐leucine zipper gene potentially involved in abscisic acid‐dependent responses to water stress in sunflower *
Author(s) -
Gago G. M.,
Almoguera C.,
Jordano J.,
Gonzalez D. H.,
Chan R. L.
Publication year - 2002
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.2002.00853.x
Subject(s) - leucine zipper , biology , abscisic acid , complementary dna , basic helix loop helix leucine zipper transcription factors , transcription factor , open reading frame , sunflower , gene , helianthus annuus , microbiology and biotechnology , bzip domain , homeobox , biochemistry , peptide sequence , dna binding protein , agronomy
Homeodomain‐leucine zipper proteins constitute a family of transcription factors found only in plants. We have characterized a full‐length cDNA encoding the sunflower homeobox‐leucine zipper protein Hahb‐4 ( Helianthus annuus h omeo b ox‐4). The complete cDNA is 674 base pairs long and contains an open reading frame of 177 amino acids that belongs to the Hd‐Zip I subfamily. Northern blot and RNAse A protection analysis show that the expression of Hahb‐4 is rapidly, strongly and reversibly induced by water deficit in whole seedlings, roots, stems and leaves. A similar fast induction of Hahb‐4 expression is observed when seedlings are subjected to a treatment with the hormone abscisic acid (ABA). Nuclei prepared from seedlings treated with ABA or subjected to water stress show a significant increase of protein(s) that specifically bind the sequence 5′‐CAAT(A/T)ATTG‐3′, recognized in vitro by Hahb‐4, suggesting that an active protein is synthesized in response to these treatments. The promoter region of the Hahb‐4 gene contains sequences that fit the consensus for a G‐box present in some AB A r esponsive e lements (ABREs). We propose that Hahb‐4 may function in signalling cascade(s) that control(s) a subset of the ABA‐mediated responses of sunflower to water stress.