Cyclophilin OsCYP20‐2 with a novel variant integrates defense and cell elongation for chilling response in rice

Coordinating stress defense and plant growth is a survival strategy for adaptation to different environments that contains a series of processes, such as, cell growth, division and differentiation. However, little is known about the coordination mechanism for protein conformation change. A cyclophilin OsCYP20‐2 with a variant interacts with SLENDER RICE1 (SLR1) and OsFSD2 in the nucleus and chloroplasts, respectively, to integrate chilling tolerance and cell elongation in rice (Oryza sativa) (FSD2, Fe-superoxide dismutase 2). Mass spectrum assay showed that OsNuCYP20‐2 localized at the nucleus (nuclear located OsCYP20‐2) was a new variant of OsCYP20‐2 that truncated 71 amino‐acid residues in N‐terminal. The loss‐of function OsCYP20‐2 mutant showed sensitivity to chilling stress with accumulation of extra reactive oxygen species (ROS). In chloroplasts, the full‐length OsCYP20‐2 promotes OsFSD2 forming homodimers which enhance its activity, eliminating the accumulation of ROS under chilling stress. However, the mutant had shorter epidermal cells in comparison with wild‐type Hwayoung (HY). In the nucleus, OsCYP20‐2 caused conformation change of SLR1 to promote its degradation for cell elongation. Our data reveal a cyclophilin with a variant with dual‐localization in chloroplasts and the nucleus, which mediate chilling tolerance and cell elongation.