HAESA and HAESA-LIKE2 activate organ abscission downstream of NEVERSHED and EVERSHED in Arabidopsis flowers

A ligand-receptor module comprised of the peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) and the receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2) activates organ abscission in Arabidopsis flowers. Another set of receptor-like kinases, including EVERSHED (EVR), restricts the extent of cell separation in abscission zones by potentially altering HAE/HSL2 localization or activity. The NEVERSHED (NEV) ADP-ribosylation factor GTPase-activating protein facilitates the intracellular movement of molecules required for organ abscission and fruit growth. Here we report further analysis of the relationship between NEV-mediated intracellular traffic, EVR activity and IDA-HAE/HSL2 signaling during flower development. Our results support a model in which cell separation is mediated by HAE/HSL2 signaling downstream of NEV and EVR. We discuss the possibility that conserved circuits control organ abscission and modulate fruit growth.