StABF1, a b-ZIP transcription factor involved in abiotic stress response and tuberization

MARÍA NOELIA MUÑIZ GARCÍA ; LUCIANA MAZZOCCHI; MARIA T TELLEZ IÑON; DANIELA A CAPIATI

Potrero de los Funes-San Luis

Congreso; - XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

ABF/AREB bZIP transcription factors mediate plant abiotic stress responses by regulating the expression of stress-related genes. These proteins bind to the abscisic acid (ABA)-responsive element (ABRE), which is the major cis-acting regulatory sequence in ABA-dependent gene expression. We have already cloned and characterized a bZIP transcription factor of the ABF/AREB subfamily from potato (Solanum tuberosum L), determining that StABF1 is able to bind to the ABRE in vitro and that its transcription is induced in response to ABA, osmotic stress and cold, suggesting that it might be a key regulator of ABA-dependent stress signaling pathways in potato. Because a stimulatory effect of ABA in tuberization has been reported, we decide to determine if StABF1 expression level is regulated during the tuber formation process using a Semi-quantitative RT-PCR approach. We found that StABF1 expression levels increased during tuber development and then decreased in the last stage (S4), when the tuber is already formed. High sucrose:nitrogen ratio, used as a tuber-inducing signal, increased StABF1 mRNA levels in leaves too. Since AREB/ABF activity is regulated by phosphorylation, in-gel kinase assays were performed to determine the phosphorylation status of StABF1 under tuber-inducing or tuberization inhibitory conditions. Interestingly, changes in phosphorylation were detected. All these observations suggest that StABF1, besides acting in stress response, might be involved in tuber development.