Clock and temperature- mediated gene expression in Nothofagus pumilio, one of the dominant woody species of the southernmost terrestrial ecosystems of the world

VERONICA ARANA; NICOLAS BELLORA; BIRGIT ZIEGENHAGEN; KATRIN HEER; PAULA MARCHELLI; MAXIMILIANO ESTRAVIS-BARCALA

Santiago de Chile

Workshop; Signat Workshop on Environmental Regulation of Plant Development; 2017

Chilenan Society of Plant Biologists

In this work we show data related to the characterization of the circadian clock and the influence of warm temperatures (34°C) on global patterns of gene expression in Nothofagus pumilio, the most abundant tree species of South American Patagonian forests. We report the isolation of central oscillator genes, and the study of the expression of two of them (TOC1 and LHY) in diurnal and circadian conditions at different temperatures. Through the analysis of RNA-seq experiments from plants grown in circadian conditions (entrainment: 12h light/12h darkness, sampling in free running conditions: continuous light, at 20° or 34°C at two moments of the day: ZT48=subjective dawn, ZT60=subjective dusk), we studied the effect of warm temperatures on the transcriptome of N. pumilio. We found evidence of the existence of at least two pathways by which warm temperatures affect gene expression. One would be triggered by an effect on the circadian clock-mediated gene regulation, in which warm temperatures down-regulate the clock-mediated promotion of growth-related genes at subjective dawn as well as the clock-mediated promotion of metabolic genes at subjective dusk. The second pathway would be triggered by the temperature itself ? independently of its influence on the clock- and includes the temperature-mediated promotion of genes related to jasmonic acid/stress responses in conjunction with the down-regulation of genes related with photosynthesis. Given this species? wide distribution range (36° to 55°S), studies related with the analysis of the N. pumilio circadian clock function and its interaction with temperature constitute an interesting strategy to address adaptation and plasticity of woody plants to different thermic and photoperiodic environments, such as those occurring across latitude.