Molecular Mechanisms of Abscission in Plants

Abscission is the genetically programmed shedding of organs such as leaves, flowers and fruits, occurring at specialised cell layers known as abscission zones (AZs). These zones differentiate early in development and become sites of cell separation in response to internal and environmental cues. A decline in polar auxin flow through the AZ often precedes sensitisation to ethylene, which in turn activates receptor-mediated signalling cascades. A central peptide ligand, IDA (INFLORESCENCE DEFICIENT IN ABSCISSION), binds to leucine-rich repeat receptor-like kinases (HAESA and HSL2) and their SERK co-receptors, initiating phosphorylation events that regulate downstream transcription factors. These factors modulate expression of cell-wall-remodelling enzymes (polygalacturonases, cellulases and expansins) that degrade middle lamellae, together with programmes of programmed cell death that facilitate tissue separation. Cross-talk between auxin, ethylene and other hormones (abscisic acid, jasmonate) fine-tunes the timing of abscission, while mechanical and developmental signals ensure that detachment occurs only under appropriate conditions. Advances in transcriptomics and proteomics have revealed conserved modules across diverse species, underpinning both fundamental understanding and applications in agriculture, from controlling fruit drop to optimising mechanical harvesting.

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Molecular Mechanisms of Abscission in Plants publication trend

The graph below shows the total number of articles in molecular mechanisms of abscission in plants across all publications each year (not limited to Nature Index journals).

Technical terms

Abscission zone (AZ): A specialised layer of cells at the base of an organ where separation occurs.

Auxin gradient: Differential distribution of the plant hormone indole-3-acetic acid that inhibits abscission when high.

IDA peptide: A small secreted peptide ligand that activates HAESA and HSL2 receptor kinases to trigger abscission.

Receptor-like kinase (RLK): A membrane-bound protein that perceives extracellular signals and transduces them via phosphorylation.

Cell-wall-remodelling enzymes: A group of hydrolases (polygalacturonases, cellulases, expansins) that loosen cell walls to enable separation.

Programmed cell death (PCD): A genetically controlled process of cellular dismantling that facilitates organ detachment.

References

1. Morphological and genetic characterization of the muscadine fruit abscission zone. Horticulture Research (2024).
2. Mechanistic insight into a peptide hormone signaling complex mediating floral organ abscission. eLife (2016).
3. Cell Wall Remodeling in Abscission Zone Cells during Ethylene-Promoted Fruit Abscission in Citrus. Frontiers in Plant Science (2017).