Regulatory Mechanisms Underlying Activation of Organ Abscission

Abstract Abscission is a tightly regulated developmental process that initiates in response to endogenous and environmental cues. In an agricultural context, regulation of abscission has substantial effects on crop productivity and quality. Crop domestication often selected against abscission of the fruit, allowing easier harvesting. A better understanding of the mechanisms underlying abscission will, therefore, inform efforts to improve crop breeding and harvesting practices. In this article, we summarize our current knowledge of the various regulatory mechanisms involved in abscission. We first review the regulation of abscission zone cells as they acquire competence in response to abscission signals. We then summarize the regulation of abscission initiation, exploring the phytohormone signals, developmental factors, and environmental cues regulating the initiation of abscission.