Onset of flowering is controlled by environmental signals such as light and temperature. Molecular-genetic studies in Arabidopsis thaliana have focused on daily light duration, or photoperiod, and transient exposure to winter-like temperatures, or vernalization. Yet ambient growth temperature, which is strongly affected by current changes in global climate2, has been largely ignored. Here, we show that genes of the autonomous pathway, previously thought only to act independently of the environment as regulators of the floral repressor FLC (ref. 1), are centrally involved in mediating the effects of ambient temperature. In contrast to wild-type plants and those mutant in other pathways, autonomous-pathway mutants flower at the same time regardless of ambient temperature. In contrast, the exaggerated temperature response of cryptochrome-2 mutants is caused by temperature-dependent redundancy with the phytochrome A photoreceptor. As with vernalization and photoperiod, ambient temperature ultimately affects expression of the floral pathway integrator FT.
Bibliographical noteFunding Information:
We thank N.Y. Kwon, C. Vu and R. You for technical assistance; T. Dabi and J. Werner for growing flc fve mutants; J.M. Martínez-Zapater for communicating unpublished information; R. Amasino, G. Coupland, M. Koornneef, I. Lee and the National Science Foundation (NSF)-supported A. thaliana stock center for material; C. Fankhauser and O. Nilsson for discussions; and R. Amasino, J. Lohmann, M. Schmid, P. Wigge and X. Wu for comments on the manuscript. M.A.B. was supported by fellowships from the Spanish Ministry of Education and Human Frontier Science Program (HFSPO), and by a grant from the Spanish Ministry of Science. J.H.A. was supported by the Korea Science and Engineering Foundation through the Plant Metabolism Research Center, Kyung Hee University, and the Crop Functional Genomics Center of the 21C Frontier Program. D.W. was supported by grants from HFSPO, NSF and United States Department of Agriculture. D.W. is a Director of the Max Planck Institute.
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