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

Abstract

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.

Keywords: OsCYP20-2; OsFSD2; SLR1; cell elongation; chilling tolerance.