In most flowering plants, fruit development is tightly coupled to pollination and fertilization, which trigger hormonal signals that initiate ovary growth. When fertilization fails, ovaries typically abort and fall off, leading to yield loss. Parthenocarpy—the ability to form fruits without fertilization—offers an alternative route to stable fruit production and higher market value, but its genetic basis remains elusive, particularly in woody fruit species. Previous studies have suggested that plant hormones such as auxin and gibberellins may induce seedless fruit development, yet how endogenous hormonal regulation is genetically controlled is still unclear. Based on these challenges, there is a strong need to investigate the molecular mechanisms underlying natural parthenocarpic fruit formation.
Researchers from Guizhou University and collaborating agricultural research institutes in China report new insights into natural seedless fruit formation in chestnut rose (Rosa sterilis), a vitamin-C-rich fruit tree with strong commercial potential. The study, published (DOI: 10.1093/hr/uhaf277) online in 2025 in Horticulture Research, demonstrates that parthenocarpic fruit development in this species is driven by gibberellin accumulation controlled by a specific gene module. By combining transcriptomics, hormone treatments, transgenic validation, and gene-silencing experiments, the team uncovered how targeted genetic regulation enables fruits to grow and mature without fertilization.
The study first tracked hormone dynamics during early fruit development and found that gibberellin levels increased sharply at the fruit-setting stage, while other hormones declined or remained stable. External application of gibberellins promoted fruit retention and growth, whereas blocking gibberellin biosynthesis caused rapid fruit drop, confirming gibberellins as a key driver of parthenocarpy. Genome-wide analysis identified 43 gibberellin oxidase genes, among which RsGA3ox9 showed strong upregulation during fruit initiation.
Functional experiments demonstrated that overexpressing RsGA3ox9 in tomato enabled seedless fruit formation under non-pollinated conditions, while silencing the gene in chestnut rose caused arrested fruit growth and abscission. Further investigation revealed that three MYB transcription factors—RsMYB3, RsMYB8, and RsMYB73—directly activate RsGA3ox9. Notably, RsMYB8 and RsMYB73 physically interact to form a transcriptional complex that enhances RsGA3ox9 expression more effectively than either factor alone. This cooperative regulation boosts gibberellin biosynthesis, promotes cell expansion, and sustains fruit development without fertilization. Together, these results establish a clear molecular pathway linking transcriptional control, hormone accumulation, and seedless fruit growth.
“This work helps explain how fruits can bypass the traditional requirement for fertilization and still develop normally,” said one of the study's senior researchers. “By identifying a precise gene module that controls gibberellin production during early fruit growth, we provide a mechanistic explanation for natural parthenocarpy in a woody fruit species. Importantly, this regulatory logic may extend beyond chestnut rose, offering a conceptual framework for understanding seedless fruit formation in other crops and opening new possibilities for genetic improvement without relying on chemical hormone treatments.”
The discovery of the RsMYB8–RsMYB73–RsGA3ox9 regulatory module has practical implications for fruit breeding and sustainable agriculture. By targeting endogenous hormone biosynthesis rather than external growth regulators, breeders may develop stable seedless varieties with improved fruit quality and reduced management costs. This strategy is particularly valuable for perennial fruit trees, where chemical induction is often inefficient or inconsistent. Beyond breeding, the findings also deepen scientific understanding of how transcriptional networks coordinate hormone-driven developmental switches. As consumer demand for seedless fruits continues to rise, insights from this study could guide the design of next-generation cultivars that combine high nutritional value with reliable yield.
###
References
DOI
10.1093/hr/uhaf277
Original Source URL
https://doi.org/10.1093/hr/uhaf277
Funding information
This project is supported by grants from the Open Foundation of Ministry of Agriculture and Rural Affairs Key Laboratory of Crop Genetic Resources and Germplasm Innovation in Karst Region (2025, Guiyang, China), the Guizhou Provincial Science and Technology Projects of China (Grant No. YQK [2023]008) as well as the Innovative Platform Construction Program of Guizhou Province, China ([2020]4001).
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.