Functional characterization of the HD-Zip transcription factor AtHB13

RIBONE, PAMELA; CHAN, RAQUEL LÍA

Congreso; . Argentine Society for Biochemistry and Molecular Biology scientific meeting SAIB 2013; 2013

HD-Zip proteins are transcription factors unique to plants, exhibiting a homeodomain (HD) associated to a Leucine zipper (Zip) motif. It has been reported that the overexpression of AtHB13, a member of HD-Zip I subfamily, confers tolerance to freezing temperatures, severe drought and salinity stress. However the natural role of this gene is largely unknown. Aiming to functional characterize this gene, T-DNA insertion mutant plants (mut13) were obtained and characterized. These (mut13) plants do not present a distinct morphological phenotype during the vegetative phase, but after bolting, longer inflorescence stems, and smaller siliques with a high percentage of unfertilized ovules than WT controls were observed. On the other hand, the promoter region of this gene was isolated and plants transformed with a construct in which this promoter directs the expression of the GUS reporter gene. Histochemical analyses of these plants indicated that the reporter gene is expressed mainly in the base of the inflorescence stem. Altogether, these observations suggest that AtHB13 participates in the regulation of the inflorescence stem development, and although no GUS expression was detected in flowers, AtHB13 seems to be essential for ovule fertilization and silique maturation.