COP1 dynamics integrate conflicting seasonal light and thermal cues in the control of Arabidopsis elongation

As the summer approaches, plants experience enhanced light inputs and warm temperatures, two environmental cues with an opposite morphogenic impact. Key components of this response are PHYTOCHROME B (phyB), EARLY FLOWERING 3 (ELF3), and CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1). Here, we used single and double mutant/overexpression lines to fit a mathematical model incorporating known interactions of these regulators. The fitted model recapitulates thermal growth of all lines used and correctly predicts thermal behavior of others not used in the fit. While thermal COP1 function is accepted to be independent of diurnal timing, our model shows that it acts at temperature signaling only during daytime. Defective response of cop1-4 mutants is epistatic to phyB-9 and elf3-8, indicating that COP1 activity is essential to transduce phyB and ELF3 thermosensory function. Our thermal model provides a unique toolbox to identify best allelic combinations enhancing climate change resilience of crops adapted to different latitudes.Research has been supported by Spanish MCIN/AEI/10.13039/501100011033/ and FEDER Una manera de hacer Europa (grant nos. PGC2018-098186-B-100 to P.C., FIS2016-78313-P to S.A., and BIO2017-90056-R/PID2020-119758RB-I00 to S.P.), besides grant BADS, no. PID2019-109320GB-100, to S.A. and P.C, and funding from University of Buenos Aires (grant no. 20020170100505BA to J.J.C.), and Agencia Nacional de Promoción Científica y Tecnológica (grant no. PICT-2019-2019-01354 to J.J.C.). The CNB and CRAG Institutes also received the “Severo Ochoa” Centers of Excellence SEV 2017-0712 (CNB) and CEX2019-000902-S (CRAG) awards from the Spanish Ministerio de Ciencia e Innovación.Peer reviewe