Expression analysis of root cell types after treatment with low pH

Cell-type specific transcriptional profiles were generated by FACS (Fluorescence Activated Cell Sorting) sorting of roots that express cell-type specific GFP-reporters. Five different GFP-reporter lines were used. FACS cell populations were isolated from roots grown under standard pH (pH 5.7) or roots that had been transfered to low pH (pH 4.6) media for 24 hours. Stress responses in plants are tightly coordinated with developmental processes, but the interaction between these pathways is poorly understood. Here we use genome-wide assays at high spatial and temporal resolution to understand the processes that lnk development and stress in the Arabidopsis root. Our meta-analysis finds little evidence for a universal stress response. Common stress responses appear to exists and, analagous to animal systems, many of them show cell-type specificity, suggesting a convergent evolutionary theme in multicellular organisms. Common stress responses may be mediated by cell identity regulators, as mutations in these genes resulted in altered responses to stress. Our results reveal surprising linkages between stress and development at cellular resolution, and show the power of multiple genome-wide datasets to elucidate biological processes. 3 replicates for each of 5 cell types for low pH and standard pH (30 samples total).