Physiological and molecular mechanisms underlying the integration of light and temperature cues in Arabidopsis thaliana seeds

Abstract

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 GERMINATION 1 (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.

Thermal adaptation and plasticity of the plant circadian clock

“…It is widely documented that light and temperature information also is integrated into the clock system to generate fine‐tuned transcriptional profiles and biological rhythms (Michael et al ., 2003a, ). For example, it is known that light and temperature cycles exert cooperative effects on the clock entrainment in Drosophila and Arabidopsis (Yoshii et al ., ; Arana et al ., ). In Arabidopsis , various clock elements mediate the integration of temperature and light cycles into the clock for optimal growth and seed germination (Arana et al ., ).…”

“…For example, it is known that light and temperature cycles exert cooperative effects on the clock entrainment in Drosophila and Arabidopsis (Yoshii et al ., ; Arana et al ., ). In Arabidopsis , various clock elements mediate the integration of temperature and light cycles into the clock for optimal growth and seed germination (Arana et al ., ). However, temperature and light cues also exert their roles through independent signaling pathways in some cases (Franklin et al ., ), obscuring the functional relationship between the two signaling cues, especially in modulating the clock function.…”

Phytochrome B regulates seed germination by integrating light and temperature signals in Nicotiana tabacum L.

“…Phytochromes regulate both light-dependent and temperature-dependent germination [5,12] and permit plants to adapt the variable environment. Phytochrome B (PHYB) is the main receptor found in Arabidopsis [1,2,18]. In this study, we discovered that PHYB regulates seed germination by integrating light and temperature signals in N. tabacum.…”

“…Two hypotheses have been proposed to explain these phenomena: (a) sensitivity of seeds increases to the preexisting Pfr; (b) the Pfr level in seeds rapidly increases or decreases at certain temperatures. Studies have discovered that PHYB is the sensor of both light and temperature [1,2], which integrates light and temperature cues in Arabidopsis seeds [18]. Nevertheless, the exact pattern of integrated signals during seed germination remains unknown.…”

Global spatial analysis of Arabidopsis natural variants implicates 5′UTR splicing of LATE ELONGATED HYPOCOTYL in responses to temperature

“…& Nimmo, 2012; Kwon, Park, Kim, Baldwin, & Park, 2014;Seo et al, 2012), for light signalling components (Mancini et al, 2016;Shikata et al, 2014;Wu et al, 2014;Zhang, Lin, & Gu, 2017), and for flowering time (Capovilla, Symeonidi, Wu, & Schmid, 2017;Melzer, 2017;Pose et al, 2013;Sureshkumar, Dent, Seleznev, Tasset, & Balasubramanian, 2016). A prominent theme emerging from these advances is the role played by the circadian clock in integrating environmental cues (Arana, Tognacca, Estravis-Barcala, Sanchez, & Botto, 2017;Ezer et al, 2017;Greenham & McClung, 2015), enabling endogenous clock rhythms to coincide with externally imposed cycles of light:dark and temperature (McClung et al, 2016;Nomoto et al, 2013;Yamashino, 2013).…”