Circadian-period variation underlies the local adaptation of photoperiodism in the short-day plant Lemna aequinoctialis

Tomoaki Muranaka; Shogo Ito; Hiroshi Kudoh; Tokitaka Oyama

doi:10.1016/j.isci.2022.104634

Circadian-period variation underlies the local adaptation of photoperiodism in the short-day plant Lemna aequinoctialis

iScience. 2022 Jun 17;25(7):104634. doi: 10.1016/j.isci.2022.104634. eCollection 2022 Jul 15.

Authors

Tomoaki Muranaka¹, Shogo Ito², Hiroshi Kudoh³, Tokitaka Oyama²

Affiliations

¹ Faculty of Agriculture, Kagoshima University, Korimoto 21-24-1, Kagoshima 890-0065, Japan.
² Department of Botany, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
³ Center for Ecological Research, Kyoto University, Hirano 2-509-3, Otsu 520-2113, Japan.

Abstract

Phenotypic variation is the basis for trait adaptation via evolutionary selection. However, the driving forces behind quantitative trait variations remain unclear owing to their complexity at the molecular level. This study focused on the natural variation of the free-running period (FRP) of the circadian clock because FRP is a determining factor of the phase phenotype of clock-dependent physiology. Lemna aequinoctialis in Japan is a paddy field duckweed that exhibits a latitudinal cline of critical day length (CDL) for short-day flowering. We collected 72 strains of L. aequinoctialis and found a significant correlation between FRPs and locally adaptive CDLs, confirming that variation in the FRP-dependent phase phenotype underlies photoperiodic adaptation. Diel transcriptome analysis revealed that the induction timing of an FT gene is key to connecting the clock phase to photoperiodism at the molecular level. This study highlights the importance of FRP as a variation resource for evolutionary adaptation.

Keywords: Plant Biology; Plant biology; Plant genetics.