Guanine-nucleotide exchange factor (GEF) that acts as an activator of Rop (Rho of plants) GTPases by promoting the exchange of GDP for GTP. Functions as a light-signaling switch that functions in root growth and development through the activation of Rop in a phytochrome-dependent manner. May act as a negative regulator of phytochrome-mediated primary root development. Interacts with ARAC4/ROP2, ARAC3/ROP, ARAC9/ROP8, PHYA and PHYB. Interacts with PHYA and PHYB in the cytoplasm in darkness. A number of isoforms are produced. According to EST sequences. Highly expressed in elongating regions of roots and pollen grains. Expressed in flowers, and at lower levels in leaves and stems. The PRONE (plant-specific Rop nucleotide exchanger) domain is responsible for the GEF activity. Plants overexpressing ROPGEF11 show retarded root elongation and irregular root hair formation. Truncated N-terminus.