HAHB-10, A SUNFLOWER HOMEOBOX-LEUCINE ZIPPER GENE, IS INVOLVED IN THE RESPONSE TO DARK/LIGHT CONDITIONS.

EVA RUEDA; CARLOS DEZAR; DANIEL GONZALEZ; RAQUEL CHAN

Iguazu

Congreso; XL Reunión de SAIB; 2004

SAIB

  Homeodomain-leucine zipper (HD-Zip) proteins constitute a family of transcription factors found only in plants. Experimental evidence indicated that these proteins are involved in regulating developmental processes associated with the response of plants to environmental conditions. We have performed functional studies on Hahb-10 (Helianthus annuus homeobox-10), a member of the Hd-Zip II subfamily of Hd-Zip proteins. Expression studies showed that this gene is expressed primarily in mature leaves and is strongly induced in seedlings when seeds are germinated and grown in the dark. A similar high induction of Hahb-10 expression was observed when seedlings were subjected to treatment with gibberellins. Transgenic Arabidopsis thaliana plants that express Hahb-10 under the control of the 35S cauliflower mosaic virus promoter were obtained. These plants showed special phenotypic characteristics like darker cotyledons and a marked acceleration of development, reducing the life cycle about 25%. These plants also showed atypical responses when treated with different light conditions. We propose that Hahb-10 may function in signalling cascade(s) that control(s) plant adaptive responses to dark/light conditions.