IDENTIFICATION OF KEY SEQUENCES IN THE HAHB-4 GENE PROMOTER FOR THE REGULATION OF ITS EXPRESSION.

CARLOS DEZAR; PABLO MANAVELLA; RAQUEL CHAN

Rosario

Congreso; XLII Reunión Anual de SAIB; 2006

SAIB

Sunflower Hahb-4 encodes a transcription factor from the HD-Zip family. Its expression is transcriptionally regulated by drought, ABA, ethylene and other abiotic stresses. In this work we describe the functional characterization of the Hahb-4 promoter, with the aim of identifying the cis elements within this regulatory segment of DNA. In order to achieve our aim we obtained several constructs bearing fractions of the promoter fused to the gus reporter gene, occasionally including chimeras and point mutations. These constructs were used to transform Arabidopsis thaliana plants. The expression patterns of the reporter gene were analyzed by histochemistry while transcript expression levels were quantified using Real-Time RT-PCR. Our results suggest that this promoter present a bipartite structure. The first region, adjacent to the transcription start point would contain functional boxes of response to hormones and also of tissue-specific expression, whereas the further one would include enhancer elements, essential for an efficient expression. Additionally, we could conclude that most of the elements identified in silico are not actually functional in this promoter..