Rice (Oryza sativa L.) is a semiaquatic plant that forms adventitious root primordia at the stem nodes as part of normal development. Upon flooding, roots emerge, preceded by local death of epidermal cells above the root primordia. Cell death is strictly confined to cells above root primordia and is induced by ethylene and H2O2. These pro-death signals regulate expression of the transcription factor genes ANT-like, OsARF2, OsARF3 and Hox9 which have a proposed function in cell type specification, boundary formation, or organ polarity. It is hypothesized that local induction of cell death is dependent on epidermal cell identity as defined at the molecular level.
Keywords: cell identity genes; epidermal cell death; ethylene; hydrogen peroxide; rice.