Plant growth and development is controlled by various environmental cues that are sensed by the plant via various signal transduction pathways coupled to specific response. Some of these pathways are conserved from yeast to plants being regulated by various kinases and phosphatases. In addition, plants have many unique pathways that transduce to specific signals such as light, phytohormones and oligosaccharides. This volume highlights some of the examples of the plant signal transduction machinery opening new vistas in research on plant growth and development. The new technologies including the use of bacteria, yeast and Arabidopsis as functional complementation systems are providing proof of function of many of the proteins that show homology to those from other organisms. These studies will eventually lead to improvement of crop plants and use of plants as a new resource for producing desirable products to meet the growing needs of mankind.