Role of the circadian clock as an integrator of light and temperature cues during germination

ARANA, MV; ESTRAVIS-BARCALÁ, M; SANCHEZ, RA; BOTTO, JF

Congreso; XXX Reunión Argentina de Fisiología Vegetal; 2014

Seeds sense a number of cues that provide information about the environment which are integrated in the regulation of developmental processes such as dormancy and germination. In several species, light and temperature are signals of outmost relevance for the modulation of dormancy level. Despite of its ecological and economic importance, the genetic mechanisms involved in the light-mediated control of dormancy in combination with temperature are scarcely known. Here we show that daily temperature cycles promote red (R)-mediated germination in Arabidopsis seeds. As in the wild type, daily temperature cycles promote the R-mediated germination of the phytochrome (phy) A lack of function mutant but, in contrast, this response is absent in the phyB mutant. Using a set of circadian clock lack of function mutants, we show that the synergism between light and temperature cycles is strongly decreased in toc1, prr7 and prr9 seeds, but it is present in lhy seeds. We propose that daily alternating temperatures entrain circadian rhythms in the seeds through loops involving TOC1, PRR7 and PRR9 components stimulating the promotion of phyB-dependent germination. The synergism between light and temperature reported here may provide the individuals with the ability to adjust patterns of germination to environments of ecological relevance.