Joanne Chory, PhD, 62, of the Salk Institute for Biological Studies in La Jolla, Calif., and Elliot Meyerowitz, PhD, 67, of the California Institute of Technology (Caltech) in Pasadena, Calif., have been pioneers in discovering and describing the basic regulatory and biochemical mechanisms underlying the development of plants. Chory identified and characterized the hormonal signaling mechanisms that are key to understanding how plants regulate their growth in response to light and other environmental signals. Meyerowitz established Arabidopsis thaliana as the unified research model for the study of plant development. He also discovered the key transcription factors and regulatory mechanisms underlying flower shapes and patterns. Their contributions have helped to revolutionize the field of plant molecular biology, with broad implications for global agriculture, the environment, and human health and disease.