Programmed cell death (PCD) is an umbrella term describing different forms of actively controlled,

genetically encoded cellular suicide. In both plants and animals, PCD has many different functions in

development and health. Yet, in comparison to animals, the knowledge of the molecular

mechanisms that control PCD in plants is still very limited. In the past, we have established the root

cap of the reference plant Arabidopsis thaliana as a novel model system for developmentally

regulated PCD (dPCD) in plants. We have identified a score of transcriptionally regulated dPCDassociated

genes, though most of their individual functions remain enigmatic. Recently, we have

discovered SOMBRERO, LIBITINA1, and LIBITINA2, three transcription factors that act as key

regulators of dPCD, being necessary for regular dPCD execution in the root cap as well as sufficient

to cause ectopic PCD upon inducible misexpression.

Here, we describe a complementary approach of reverse and forward genetics to identify additional

modules of the dPCD regulatory network downstream of SOMBRERO, LIBITINA1, and LIBITINA2, and

upstream of the score of dPCD-associated genes. To this end, we have devised a strategy combining

latest CRISPR technology, protein-DNA interaction assays, and a powerful forward genetics mutant

screen. Adding new modulators to the still sketchy dPCD regulatory network will be crucial for our

understanding of PCD as a fundamental developmental process in plants.