PLURIPETALA mediates ROP 2 localization and stability in parallel to SCN 1 but synergistically with TIP 1 in root hairs

Summary Prenylation, the post‐translational attachment of prenyl groups to substrate proteins, can affect their distribution and interactomes. Arabidopsis PLURIPETALA ( PLP ) encodes the shared α subunit of two heterodimeric protein isoprenyltransferases, whose functional loss provides a unique opportunity to study developmental and cellular processes mediated by its prenylated substrates, such as ROP GTP ases. As molecular switches, the distribution and activation of ROP s are mediated by various factors, including guanine nucleotide exchange factors, GTP ase activating proteins, guanine nucleotide dissociation inhibitors (Rho GDI s), prenylation, and S ‐acylation. However, how these factors together ensure that dynamic ROP signalling is still obscure. We report here that a loss‐of‐function allele of PLP resulted in cytoplasmic accumulation of ROP 2 in root hairs and reduced its stability. Consequently, two downstream events of ROP signalling, i.e. actin microfilament ( MF ) organization and the production of reactive oxygen species ( ROS ), were compromised. Genetic, cytological and biochemical evidence supports an additive interaction between prenylation and Rho GDI 1/ SCN 1 in ROP 2 distribution and stability whereas PLP acts synergistically with the protein S ‐acyl transferase TIP GROWTH DEFECTIVE 1 during root hair growth. By using root hair growth as a model system, we uncovered complex interactions among prenylation, Rho GDI s, and S ‐acylation in dynamic ROP signalling.