REGULATION OF PUTATIVE P1 TARGETS IN LEAVES OF HIGH ALTITUDE MAIZE LANDRACES UNDER UV-B CONDITIONS

EMILIANI, J.; RIUS, S.P.; GROTEWOLD, E.; CASATI, P.

Puerto Madryn, Chubut , República Argentina

Congreso; XLVI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

P1 is a R2R3-MYB transcription factor that regulates the accumulation of a specific group of flavonoids in maize floral tissues; among them the flavones and phlobaphenes. At present, only a few genes that encode for enzymes in the last steps of flavonoid biosynthesis have been demonstrated to be P1 targets. Recently, RNA-Seq have identified 777 genes significantly higher in red maize pericarps expressing the P1-rr allele, than in white P1-ww pericarps. This list includes all known P1 regulated genes, as well as other new putative targets. In this list, a number of transcription factors, enzymes of the cell wall biosynthesis and other pathways were identified. In this work, we have analyzed the transcriptional regulation of these genes by UV-B in leaf tissues of different maize high altitude landraces that express different P1 alleles that are expressed in leaves and are also UV-B regulated, and in a low altitude line (W23 b, pl) as a control. Our results show aninduction of almost all the analyzed genes in the different lines by UV-B. Also, in the high altitude landraces, some transcripts have already higher levels in the absence of UV-B than in the W23 line (e.g. RHS1, PAL3, JAC1). In conclusion, P1 is probably involved in an overall adaptive response to UV-B radiation in maize leaves, regulating the expression different targets besides the well characterized flavonoid pathway.