Cell-Type-Specific Responses to DNA Damage

A single chromosomal break can induce the loss of hundreds of genes. For this reason, all organisms have the ability to detect even a single double-strand break, initiating a response that includes the induction of repair, the arrest of cell division, changes in developmental fate, and in some cases programmed cell death (PCD).  These responses vary from organism to organism, with cell type, and even with the time of day.  The cell-type specificity of damage response has not been well charac­terized in any model system. Plants exhibit a robust transcriptional response to chromosomal breaks,  involving the induction or suppression of thousands of genes.  New technologies allow us to rapidly purify nuclei or cells from specific cell types.  I will discuss our efforts to compare and contrast the transcriptional response in very specific cell types.  I will focus on a small and specialized population of cells within the plant root tip which undergo PCD in response to breaks. This approach may allow us to identify novel genes required for break-induced programmed cell death, and also provides markers that allow us to visualize early steps in the induction of PCD in plants.