Plant seeds: An exciting model system for dissecting molecular and cellular regulation of metabolic processes

Metabolic processes are regulated by complex networks of interacting mechanisms that utilize various cellular machineries. Such complex networks may be well exemplified by the synthesis, accumulation, and degradation of storage proteins in developing and germinating seeds. Our laboratories are using plant seeds as a model system for studying the regulation of production of the essential amino acid lysine, the control of synthesis of storage proteins and their transport to the storage vacuoles, and the de novo formation of new forms of lytic vacuoles in germinating seeds which fuse with the storage vacuoles to enable degradation of the storage protein sand their mobilization into the germinating embryo. We show that: (i) production of lysine in developing seeds is regulated by complex pathways of synthesis and catabolism that involve the sensing of free lysine levels in the seeds, and (ii) analysis of the deposition of storage proteins in seed storage vacuoles and their subsequent degradation during germination provide novel insights into the biogenesis and function of vacuoles in plants.