Divergence in red light responses associated with thermal reversion of phytochrome B between high‐ and low‐latitude species

Summary
・Phytochromes play a central role in mediating adaptive responses to light and temperature throughout plant life cycles. Despite evidence for adaptive importance of natural variation in phytochromes, little information is known about molecular mechanisms that modulate physiological responses of phytochromes in nature.
・We show evolutionary divergence in physiological responses relevant to thermal stability of a physiologically active form of phytochrome (Pfr) between two sister species of Brassicaceae growing at different latitudes.
The higher latitude species (Cardamine bellidifolia; Cb) responded more strongly to light‐limited conditions compared with its lower latitude sister (C. nipponica; Cn). Moreover, CbPHYB conferred stronger responses to both light‐limited and warm conditions in the phyB‐deficient mutant of Arabidopsis thaliana than CnPHYB: that is Pfr CbphyB was more stable in nuclei than CnphyB.
・Our findings suggest that fine tuning Pfr stability is a fundamental mechanism for plants to optimise phytochrome‐related traits in their evolution and adapt to spatially varying environments, and open a new avenue to understand molecular mechanisms that fine tune phytochrome responses in nature.

This is the peer reviewed version of the following article: Ikeda, H., Suzuki, T., Oka, Y., Gustafsson, A.L.S., Brochmann, C., Mochizuki, N. and Nagatani, A. (2021), Divergence in red light responses associated with thermal reversion of phytochrome B between high- and low-latitude species. New Phytol, 231: 75-84., which has been published in final form at https://doi.org/10.1111/nph.17381. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages there of by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.