Fecha de publicación: -- Fuente: PubMed "plant biotechnology" New Phytol. 2026 Oct 20. doi: 10.1111/nph.71650. Online ahead of print.ABSTRACTRho-related GTPases of plants (ROPs) are evolutionarily conserved molecular switches that typically maintain PIN-formed proteins at the plasma membrane (PM), yet their functional divergence remains poorly understood. Here, we reveal that a single amino-acid substitution at residue 194 acts as a core determinant, driving the evolutionary split between Brassicaceae and Malvaceae ROP6 orthologs: glycine enforces PM stabilization, whereas alanine licenses endocytic function. In cotton, the Malvaceae-predominant alanine mutated GhROP6 displays an auxin-independent manner. The distinct activity is attributed to the recruitment of three GhRIC effectors that directly bind the actin cytoskeleton and promote F-actin assembly and bundling. The resulting actin reorganization facilitates GhPIN3a internalization and proteolysis, consequently enhancing cotton fiber elongation. Our findings demonstrate that a single amino-acid change can reprogram ROP signaling and uncover a molecular switch underlying the functional evolution of ROP6 in regulating plant development.PMID:42899453 | DOI:10.1111/nph.71650