FUNCTIONAL CHARACTERIZATION OF THE HAHB10 GENE

DEZAR CA, MANAVELLA PA AND CHAN RL

Mar del Plata, Bs As, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Hahb-10 sunflower gene encodes a transcription factor from the HD-Zip family. Its expression is transcriptionally regulated by etiolation and GA, and its overexpression in rabidopsis thaliana produces a shortening of the life cycle. Here we report the isolation from a sunflower genomic library of a 1270 bp Hahb-10 promoter region. In silico analysis of its sequence revealed the presence of cis-elements putatively involved in etiolation and gibberelin signalling among others.Aiming to investigate the functionality of such cis-elements we prepared constructs bearing fractions of this promoter fused to GUS and transformed Arabidopsis plants with them. The expression patterns obtained by histochemistry showed high expression in the reproductive state, essentially in stem and anthers. Moreover, the activity of the promoter was strong in etiolated seedling in accordance with the expression studies done in sunflower. Additionally, plants transformed with the whole gene show a phenotype similar to the one shown by those transformed with the construct 35S:HAHB10 indicating that this promoter is well recognized in Arabidopsis. We can conclude that HAHB10 participates in light signaling pathways specially in process like etiolation and flowering.