P1 epigenetic regulation in leaves of high altitude maize landraces: effect of UV-B radiation

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

Front. Plant Sci.

Frontiers Editorial

Lugar: Lausanne; Año: 2016 vol. 7

P1 is a R2R3-MYB transcription factor that regulates the accumulation of a specific group of flavonoids in maize floral tissues, suchas flavones and phlobaphenes. P1 is also highly expressed in leaves of maize landraces adapted to high altitudes and higher levels ofUV-B radiation. In this work, we analyzed the epigenetic regulation of the P1 gene by UV-B in leaves of different maize landraces.Our results demonstrate that DNA methylation in the P1 proximal promoter, intron1 and intron2 is decreased by UV-B in all linesanalyzed; however, the basal DNA methylation levels are lower in the landraces than in B73, a low altitude inbred line. DNAdemethylation by UV-B is accompanied by a decrease in H3 methylation at Lys 9 and 27, and by an increase in H3 acetylation.smRNAs complementary to specific regions of the proximal promoter and of intron 2 3´ end are also decreased by UV-B;interestingly, P1 smRNA levels are lower in the landraces than in B73 both under control conditions and after UV-B exposure,suggesting that smRNAs regulate P1 expression by UV-B in maize leaves. Finally, we investigated if different P1 targets in flowertissues are also regulated by this transcription factor in response to UV-B. Some targets analyzed show an induction in maizelandraces in response to UV-B, with higher basal expression levels in the landraces than in B73; however, not all the transcriptsanalyzed were found to be regulated by UV-B in leaves.