Higher plants display a variety of architectures that are defined by the degree of branching, intermodal elongation and shoot determination. Studies on a number of nodal plants including Arabidopsis thaliana have greatly strengthened our understanding on the molecular genetic basis of plant architecture; Cytokinins (CK) and auxins are the plant specific chemical messengers (hormones), yet they elicits a diverse array of responses and is involved in the regulation of growth and development throughout the plant life cycle. The recent identification of mutants that are defective in plant architecture and characterization of the corresponding and related genes will eventually enable us to elucidate the molecular mechanisms underlying CK signaling and plant architecture. Forward and reverse genetics strategies have identification important molecular components in auxins-CK perception, signaling and transport. These advances resulted in the identification of some of the underlying regulatory mechanisms as well as the emergence of functional frameworks for auxins-CK action. Furthermore, one prominent mechanism for auxins-CK signal transduction involves degradation of the targeted members of a family of transcriptional regulators participate in complex and competing dimerization networks to modulate the expression of a wide range of genes. These achievements allowed us to improve the plants architecture by molecular design to enhancing crop productivity.