Dissection of the IDA promoter identifies WRKY transcription factors as abscission regulators in Arabidopsis.

Plants shed organs like leaves, petals or fruits through the process of abscission. Monitoring cues like age, resource availability, biotic and abiotic stresses allows plants to abscise organs in a timely manner. How these signals are integrated in the molecular pathways that drive abscission is largely unknown. The INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) gene is one of the main drivers of floral organ abscission in Arabidopsis and is known to transcriptionally respond to most abscission-regulating cues. Interrogating the IDA promoter in silico and in vitro we identified transcription factors that can potentially modulate IDA expression. We probed the importance of ERF and WRKY binding sites for IDA expression during floral organ abscission, with WRKYs being of special relevance to mediate IDA upregulation in response to biotic stress in tissues destined for separation. We further characterized WRKY57 as a positive regulator of IDA and IDA-like gene expression in abscission zones. Our findings highlight the promise of promoter element-targeted approaches to modulate the responsiveness of the IDA signaling pathway to harness controlled abscission timing for improved crop productivity.