EPIGENETIC REGULATION OF P1 IN LEAVES OF HIGH ALTITUDE MAIZE LANDRACES: EFFECT OF UV-B RADIATION

RIUS, S.P.; EMILIANI, J.; FALCONE FERREYRA, M.L.; CASATI, P.

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Congreso; L Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014

P1 is a R2R3-MYB transcription factor (TF) that regulates the accumulation of a specific group of flavonoids in maize floral tissues; among them the flavones and phlobaphenes. Maize landraces adapted to high altitude also express P1 in leaves. In this work, we have analyzed the epigenetic regulation of the P1 gene in leaf tissues of different landraces at the level of DNA methylation and histone modifications, and also investigated if different P1 targets, which were identified in pericarps, are also regulated by this TF in response to UV-B. Our results show a decrease in the percentage of DNA methylation of three different P1 regions by UV-B (proximal promoter, intron1 and intron2). This DNA modification is accompanied by a decrease/increment in the level of histone methylation/acetylation of histones, respectively. We also observed that the basal DNA methylation levels are lower in the landraces respect to B73, a low altitude line. The transcript levels of some P1 targets in leaves show an induction in the analyzed landraces in response to UV-B, and also higher basal expression levels in comparison to B73. In conclusion, P1 expression is regulated epigenetically promoting the expression of this TF, which in turn regulates the expression of different target genes, some of them involved in the synthesis of flavonoids in response to UV-B in maize leaves.