The research in my lab focuses on two inter-related questions: How do multi-cellular organisms construct specialized cells and how do the genetic components of specialized cells change over evolutionary scales? The goal is to better understand how gene regulatory networks orchestrate cell maturation, a process that results in a set of highly specialized cell types. Thus, we focus on cellular differentiation, which is one of the key steps in organ formation and development in higher organisms. The approach of the lab combines genomics and molecular genetic tools. For example, we have pioneered a new technique to isolate cell types in plants using high-speed fluidics. From there, RNA from a specific cell type population is applied to microarrays to provide a profile of gene activity at the transcriptional level. Transcriptional profiles of cells can then be used to identify likely cell-specific regulators and infer properties of the genetic circuitry of cellular specification. Two experimental approaches are being used to address this larger question. The first project is large-scale reverse genetics guided by a detailed map of gene expression in the root and other organs. As a case study in cellular development, we have started to analyze knockouts of genes that are highly enriched in xylem, which are the water-conducting cells of the plant's vascular system. We also use computational approaches to generate testable hypotheses on the targets of transcription factors that control xylem maturation. The second project is creating detailed maps of gene expression in the roots of other plant species, such as rice. This will help us to track changes in gene expression during evolution. We can then ask how genetic networks have changed over time to create new cellular attributes and, occasionally, new cell types.