Functional Identification of PavRAP2.3 Highlights the Involvement in Regulation of Sweet Cherry Fruit Abscission.

APETALA2/ethylene response factor (AP2/ERF) transcription factors constitute a significant family of transcription factors that play crucial roles in plant growth and development. Meanwhile, organ abscission is common in the growth and development of fruit trees. In particular, the economically important sweet cherry (Prunus avium L.) is highly affected by excessive fruit abscission, limiting its yield and economic benefits. Previous research identified the potential involvement of PavRAP2.3 (RELATED TO AP2.3) of the AP2/ERF family in fruit abscission based on the significantly higher PavRAP2.3 expression levels in abscised tissues. This study found the highest PavRAP2.3 expression level in mature fruits and significantly increased PavRAP2.3 expression in leaves treated with abscisic acid (ABA) and ethephon (ETH). PavRAP2.3 was localized in the nucleus and exhibited transcriptional activity in Y2H gold yeast. Yeast one-hybrid assays and dual-luciferase assays revealed that PavRAP2.3 induced abscission by regulating the PavCEL9-like, a gene associated with cell wall reconstruction. Furthermore, PavRAP2.3-overexpressing Arabidopsis thaliana exhibited promoted petal abscission, which was attributed to the upregulation of Cellulase 3 (CEL3), Mannase 7 (MAN7), ABA Insensitive 5 (ABI5), and ACC SYNTHASE6 (ACS6) genes. Therefore, PavRAP2.3 functions as a positive regulator involved in sweet cherry fruit abscission, chiefly via regulating PavCEL9-like. These findings could facilitate breeding efforts aimed at reducing fruit abscission in sweet cherry, as well as better the understanding of the function of the AP2/ERF family.