A new transcription factor coding gene induced by water deficit or abscisic acid of Helianthus annuus, having a homeodomain associated to a leucine zipper, was characterized. The transcription factor is useful to be cloned in DNA constructions for transforming host cells and plants. The transgenic plants comprising the transcription factor gene are tolerant and resistant to harmful environmental conditions such as water stress and high salinity. A nucleic acid promoting sequence is also provided wherein the sequence is induced by water deficit or abscisic acid. Constructions, host cells and transgenic plants that comprise the transcription factor gene are provided.