PHYSIOLOGICAL AND MOLECULAR MECHANISMS UNDERLYING THE INTEGRATION OF LIGHT AND TEMPERATURE CUES IN ARABIDOPSIS THALIANA SEEDS.

The relief of dormancy and the promotion of seed germination are of extreme importance for a successful seedling establishment. Although alternating temperatures and light are signals promoting the relief of seed dormancy, the underlying mechanisms of their interaction in seeds are scarcely known. By exposing imbibed Arabidopsis thaliana dormant seeds to two-day temperature cycles previous of a red light pulse, we demonstrate that the germination mediated by phytochrome B requires the presence of functional PSEUDO-RESPONSE REGULATOR 7(PRR7) and TIMING OF CAB EXPRESSION 1(TOC1) alleles. In addition, daily cycles of alternating temperatures in darkness reduce the protein levels of DELAY OF GERMINATION1(DOG1), allowing the expression of TOC1 to induce seed germination. Our results suggest a functional role for some components of the circadian clock related with the action of DOG1 for the integration of alternating temperatures and light signals in the relief of seed dormancy. The synchronization of germination by the synergic action of light and temperature through the activity of circadian clock might have ecological and adaptive consequences. This work studies the function of alternating temperatures in dormancy and germination of Arabidopsis thaliana seeds. We demonstrated that the incubation of dormant seeds at 15 degrees C/23 degrees C alternating temperature cycles for 2days is sufficient to enhance the light response of seeds. The results suggest a functional role for some components of the circadian clock related with the action of DOG1 for the integration of alternating temperatures and light signals in the relief of seed dormancy.