Figure 8.

Model of Epidermal Cell Death Signaling.

Submergence leads to accumulation of ethylene, which in turn results in elevated H₂O₂ levels through H₂O₂ synthesis by NADPH oxidase and reduced scavenging from downregulated MT2b. Positive feedback loops exist between H₂O₂ and MT2b as well as between H₂O₂ and the ethylene biosynthetic genes ACO1 and EOL1, resulting in a self-enhanced amplification of both ethylene and H₂O₂ signaling. H₂O₂ further acts as a signal that alters expression of additional genes involved in cell death.