Trafficking pathways in eukaryotes, their regulatory mechanisms as well as the molecular machinery involved are relatively well understood. However, the underlying genetic regulation has been largely overlooked. The question how cells adapt to various trafficking requirements, and to which extent this regulation is transcriptionally controlled, is of great importance to the field of cell biology and development. In this project, I want to address this question using Arabidopsis seed storage protein trafficking. Late in embryogenesis, large quantities of storage proteins are transported into a novel type of organelle, the storage vacuole. This process is most likely transcriptionally regulated, as it occurs only during this stage of development. Recently, genes involved in this event have been identified in the host laboratory and other groups. I aim to identify the transcriptional regulation of these in order to decipher common cis-regulatory elements, their transcription factors and/or epigenetic regulators. The identified regulators will be first analyzed for functional significance in storage vacuole trafficking. Further analyses will shed light on the fundamental question whether all these responses are developmentally programmed, or whether cells can actually sense their current transport requirements. The proposal is, to my knowledge, the first specifically aimed at the interface between transcriptional control and a cell biological phenomenon. Thus, the proposed project will not only be of interest to plant storage protein trafficking, but also lead to a better understanding of the genetic regulation of plant protein trafficking in general and even other eukaryotic systems, exploring potentially conserved mechanisms. Eventually, identifying the main regulators of storage protein trafficking may also enable altering the storage capacity in vegetative tissues, a trait much sought after in applied plant research to utilize crop plants as biofactories.