Vacuolar Protein Sorting 26C encodes an evolutionarily conserved large retromer subunit in eukaryotes that is important for root hair growth in Arabidopsis thaliana

Summary The large retromer complex participates in diverse endosomal trafficking pathways and is essential for plant developmental programs, including cell polarity, programmed cell death and shoot gravitropism in Arabidopsis. Here we demonstrate that an evolutionarily conserved VPS 26 protein ( VPS 26C; At1G48550) functions in a complex with VPS 35A and VPS 29 necessary for root hair growth in Arabidopsis. Bimolecular fluorescence complementation showed that VPS 26C forms a complex with VPS 35A in the presence of VPS 29, and this is supported by genetic studies showing that vps29 and vps35a mutants exhibit altered root hair growth. Genetic analysis also demonstrated an interaction between a VPS 26C trafficking pathway and one involving the SNARE VTI 13 . Phylogenetic analysis indicates that VPS 26C , with the notable exception of grasses, has been maintained in the genomes of most major plant clades since its evolution at the base of eukaryotes. To test the model that VPS 26C orthologs in animal and plant species share a conserved function, we generated transgenic lines expressing GFP fused with the VPS 26C human ortholog ( Hs DSCR 3 ) in a vps26c background. These studies illustrate that GFP ‐Hs DSCR 3 is able to complement the vps26c root hair phenotype in Arabidopsis, indicating a deep conservation of cellular function for this large retromer subunit across plant and animal kingdoms.