From flowering to fruit maturity, plants rely on a finely tuned hormonal orchestra to regulate development. While auxin, gibberellin, and abscisic acid have been widely studied for their stage-specific roles, ethylene has traditionally been cast as a ripening cue—especially in climacteric fruits. Yet, a growing body of research now points to ethylene’s involvement much earlier in the reproductive process. In cucurbits, it governs whether flowers become male or female. In tomatoes, it modulates pollen tube behavior. And across multiple species, it influences fruit size in a dosage-sensitive manner. Due to these emerging complexities, there is an urgent need to explore ethylene’s broader biological functions in detail.
A comprehensive review (DOI: 10.1093/hr/uhae229) published on August 9, 2024, in Horticulture Research by researchers at BGI and the Southern University of Science and Technology sheds new light on ethylene’s expanding role in fruit biology. Drawing from genetic, molecular, and physiological studies across diverse plant species, the authors argue that ethylene—and its signaling components—are deeply involved in sex determination, fruit set, and early growth stages, challenging the long-held notion that its influence is confined to ripening.
The review maps out how ethylene orchestrates key developmental milestones beyond ripening. In cucumber and melon, ethylene determines flower sex by regulating ACS and WIP1 gene networks, creating feedback loops that influence whether a flower becomes male or female—insights that are already informing gene-editing strategies for improved crop yields. In tomatoes, ethylene acts during fruit set to fine-tune pollen tube growth and prevent multiple fertilizations, with mutants in EIN2 and EIN3 demonstrating how ethylene signaling, rather than the gas itself, is essential for reproductive success. Even more surprising, ethylene precursors like ACC have been shown to act independently in guiding fertilization processes.
When it comes to fruit growth, ethylene’s effect is more nuanced. Both overproduction and suppression can result in smaller fruits, indicating a finely balanced “just right” threshold. In cucumbers, mutants with altered ethylene levels display reduced cell division. In rice, ethylene signaling boosts grain size, while in maize, it curbs ear length—underscoring the hormone’s species- and tissue-specific actions. Together, these findings position ethylene as a central—but context-dependent—player in fruit development.
“Ethylene has long been studied as a ripening hormone, but it’s increasingly clear that its impact begins far earlier in fruit development,” said Dr. Wei Huang, lead author of the review. “What’s especially exciting is the discovery that certain ethylene components can act independently of the gas itself, opening up entirely new regulatory possibilities. These findings challenge long-held assumptions and could significantly advance how we breed crops for yield, quality, and resilience.”
The broader understanding of ethylene’s roles could reshape strategies for horticultural crop improvement. By fine-tuning ethylene levels or modifying specific signaling components, breeders may one day precisely control flower sex ratios, delay premature fruit drop, or optimize fruit size without compromising quality. The recognition that EIN2, EIN3, and ACC can function independently suggests new pathways for targeted trait manipulation. Moreover, the integration of emerging tools like single-cell transcriptomics and epigenomics will enable researchers to map ethylene signaling across different tissues and developmental stages. Such advances promise to elevate hormone-guided agriculture into a new era of precision and sustainability.
###
References
DOI
10.1093/hr/uhae229
Original Source URL
https://doi.org/10.1093/hr/uhae229
Funding information
This work was supported by the National Natural Science Foundation of China (32200263 to W.H.), the Shenzhen Science and Technology Program (KQTD20190929173906742 to H.G. and KQTD20230301092839007 to C.T.), the Science and Technology Major Special Project of Shenzhen (KJZD20230923114607016 to W.H.), and the Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture (AGIS-ZDXM202201 to H.G.)
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.