A RAF–SnRK2–PP2C functional module regulates cell survival in the chlorophyte Chlamydomonas reinhardtii

ABSTRACT: The SNF1-related protein kinase 2 (SnRK2) pathway is a central regulator of abiotic stress signaling in land plants; however, its evolutionary origins and functional conservation across the green lineage remain poorly understood. Land plants evolved from streptophyte algae, whereas the chlorophyte algae, including the widely studied model Chlamydomonas reinhardtii, represent an older lineage that diverged from streptophytes over one billion years ago. Here, we identify and characterize a functional SnRK2 signaling module in Chlamydomonas reinhardtii. We show that the isoform SnRK2.7 is required for osmotic stress tolerance and general cellular viability, thus offering an alternative model for dissecting SnRK2 functions in algae. SnRK2.7 localizes to the contractile vacuole, an osmoregulatory organelle lost during streptophyte evolution, revealing a lineage-specific functional adaptation. Together with MAPKKK3, a B1/B3-RAF kinase, and the clade A protein phosphatase PP2C3, these components constitute a SnRK2 signaling module in Chlamydomonas reinhardtii. Our findings demonstrate the presence of a functional SnRK2 pathway in a chlorophyte alga, indicating that core components were established early in the green lineage. This work provides a foundation for comparative studies across green plants and underscores the need for broader taxonomic sampling to reconstruct the ancestral signaling networks underlying stress adaptation.

INSTRUMENT(S):

ORGANISM(S): Chlamydomonas Reinhardtii

TISSUE(S): Cell Culture

SUBMITTER: GKN JK  

LAB HEAD: xiaobo li

PROVIDER: PXD079084 | Pride | 2026-07-02

REPOSITORIES: Pride