Regulation of the expression of Genes in Plants by Photoreceptors: Effects of Deletions and Subtitutions of CAB Promoter

MARÍA JOSÉ RODRÍGUEZ BATILLER, PAULA M. SEMERDJIÁN, MARÍA A. HUBER, ROBERTO J. STANELONI, RODOLFO A. SÁNCHEZ, Y JORGE CASAL

Villa Carlos Paz, Córdoba

Congreso; Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB 2001); 2001

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

Ligth is one of the most important factors in the develoment of plants. They have systems that allow them to perceive the quality and intensity of the ligth. There are specific photoreceptors that register the light signal, which is transduced producing changes in the expression of genes.The promoter of CAB gene (Clorophyll a-b-binding protein) is regulated by light through the phytochrome system which responds to low (VLFR) and high flows (HIR) of far red light, perceived by phytochrome A, and intermediate flows of red light (LFR) through phytochrome B. In previous works we have established that a fragment of 146 bp of CAB promoter is enough to confer these tree modes of action of phytochrome. In this work we have studied the effects of successive deletions in promoter of CAB gene promoter fused to GUS gene reporter. We found a fragment of 104 bp that retains VLFR responces, perceived by phytochrome A, and LFR responses, perceived by phytochrome B. However, this fragment lacks HIR responses, also mediated by phytochrome A. This one indicates that for the first time the chains of transduction of these phytochromes can be separated at level of CAB promoter.To identify the specific sequences necessary for the HIR mode of action we made subtitutions between the regions of 146 bp and 104 bp if CAB promoter. We find a specific sequence of nucleotides where the response to high flows of far red light is lost. Thus, this specific sequence would be directly related with the HIR response.