Plant G? Structure and Properties -- Regulatory and Cellular Functions of Plant RhoGAPs and RhoGDIs -- Structure and Function of ROPs and their GEFs -- Protein-Lipid Modifications and Targeting of ROP/RAC and Heterotrimeric G Proteins -- ROP GTPases and the Cytoskeleton -- RAC/ROP GTPases in the Regulation of Polarity and Polar Cell Growth -- Heterotrimeric G Proteins and Plant Hormone Signaling in Rice -- Auxin, Brassinosteroids, and G-Protein Signaling -- Heterotrimeric G-Proteins and Cell Division in Plants -- Heterotrimeric G Protein Regulation of Stomatal Movements -- The Role of Seven-Transmembrane Domain MLO Proteins, Heterotrimeric G-Proteins, and Monomeric RAC/ROPs in Plant Defense -- G Proteins and Plant Innate Immunity -- Bioinformatics of Seven-Transmembrane Receptors in Plant Genomes -- Unconventional GTP-Binding Proteins in Plants -- Evolution of the ROP GTPase Signaling Module. This volume focuses on structure, function and regulation of plant signaling G proteins and their function in hormonal pathways, polarity, differentiation, morphogenesis and responses to biotic and abiotic stresses. Plants are sessile organisms that need to continuously coordinate between external and internal cues. This coordination requires the existence of hubs to allow cross-talk between different signaling pathways. A single family of Rho GTPases termed either ROPS or RACs and heterotrimeric G proteins have emerged as the major molecular switches in multitude of signal transduction pathway in plants.