|MEIR, SHIMON - Volcani Center (ARO)|
|PHILOSOPH-HADAS, SONIA - Volcani Center (ARO)|
|RIOV, JOSEPH - Hebrew University Of Jerusalem|
|TUCKER, MARK - Retired ARS Employee|
|PATTERSON, SARA - University Of Wisconsin|
|ROBERTS, JEREMY - University Of Plymouth|
Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2019
Publication Date: 2/6/2019
Citation: Meir, S., Philosoph-Hadas, S., Riov, J., Tucker, M., Patterson, S.E., Roberts, J.A. 2019. Re-evaluation of the ethylene-dependent and -independent pathways in the regulation of floral and organ abscission. Journal of Experimental Botany. 70(5):1461-1467. https://doi.org/10.1093/jxb/erz038.
Interpretive Summary: For flowering plants, abscission is the process whereby leaves, flowers, or fruits fall off from stems. Knowing how and when abscission occurs is important to agriculture because it affects crop harvests. Abscission is regulated at a cellular level. Hormones act together to cause a small region of cells to separate from each other. This paper reviews contemporary literature on the subject matter and discusses the various roles played by the hormones auxin, ethylene, and IDA. This review will be of interest to plant biologists at government agencies, private institutions or universities who are interested in the biochemical regulation of leaf, flower, and fruit drop.
Technical Abstract: Abscission is a developmental process with important implications for agricultural practices. Ethylene has long been considered as a key regulator of the abscission process. The existence of an ethylene-independent abscission pathway, controlled by the complex of INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) peptide and the HAESA (HAE) and HAESA-like2 (HSL2) kinases, has been proposed, based mainly on observations that organ abscission in ethylene-insensitive mutants was delayed but not inhibited. A recent review on plant organ abscission signaling highlighted the IDA–HAE–HSL2 components as the regulators of organ abscission, while the role of auxin and ethylene in this process was hardly addressed. After a careful analysis of the relevant abscission literature, we propose that the IDA–HAE–HSL2 pathway is essential for the final stages of organ abscission, while ethylene plays a major role in its initiation and progression. We discuss the view that the IDA–HAE–HSL2 pathway is ethylene independent, and present recent evidence showing that ethylene activates the IDA–HAE–HSL2 complex. We conclude that the ability of an organ to abscise is tightly linked to cell turgidity in the abscission zone, and suggest that lack of cell turgidity might contribute to the failure of floral organ abscission in the ida mutants.