image: Complete process of flower development of C. sinense and seasonal distribution of different development stages. A, B First stage of flower development (S1). Flower development starts with the appearance of a floral buttress on the shoot flank that forms a flower primordium (fp). C–E Differentiation of the flower primordia into sepal, petal, lip, and column primordia. F, G Second stage of flower development (S2). The second stage denotes slow elongation of the inflorescence meristem for 3–4 months. H Complete cycle of flowering from vegetative to reproductive phase transition and blooming in the next year. The vegetative growth lasts >2 years and then transition occurs in July. After a short period of flower initiation, the floral buds enter a period of semidormancy that lasts >3 months. Flower development resumes in November and blooming occurs in February of the next year. I Visual display of five stages of flower development (S1–S5). S1 and S2 undergo semidormancy before resuming flower development from S3. S4 represents complete flower formation and S5 denotes fully opened flowers. Lower row shows the vertical dissection of floral bud from S1 to S4, while S5 shows the complete flower with its organs.
Credit: Horticulture Research
A cutting-edge study has uncovered the complex hormonal and genetic interactions that dictate the seasonal flowering cycle of Cymbidium sinense, the Chinese orchid. This research sheds light on the enigmatic mechanisms of floral bud dormancy and its subsequent activation, offering new perspectives on the control of flowering times in plants.
Flower development in plants is a complex process influenced by various intrinsic and extrinsic factors. Hormones like gibberellin (GA) and abscisic acid (ABA) play pivotal roles in regulating this process. In many orchids, including the Chinese Cymbidium, flower bud dormancy is essential for surviving adverse conditions and ensuring timely blooming. Despite its significance, the precise molecular mechanisms underlying floral bud initiation and dormancy remain poorly understood. Based on these challenges, it is crucial to conduct in-depth studies on the hormonal regulation of flower development.
Researchers from the Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization have made significant strides in this area. Published (DOI: 10.1093/hr/uhae073) in the prestigious journal Horticulture Research, the study integrates proteomic, transcriptomic, and metabolomic profiling to elucidate the regulatory networks of Cymbidium sinense's floral development. The research highlights how GA and ABA are central to the processes of floral bud dormancy and activation, providing a detailed view of the genetic and hormonal interactions at play.
The research utilized a comprehensive multi-omics approach, analyzing proteomic, transcriptomic, and metabolomic data across six stages of flower development in Chinese Cymbidium orchids. The study revealed that GA and ABA are central regulators in the floral bud dormancy and activation process. Transcriptome and proteome analyses identified 10 gene modules with crucial roles in these stages. Early-stage gene clusters were primarily associated with flowering time regulation and meristem determination, while late-stage clusters were linked to hormone signaling pathways. The metabolomic analysis identified 69 potential hormones, highlighting GA and ABA as key regulatory hubs. Exogenous GA application accelerated bud elongation and upregulated flower development genes, whereas ABA application prolonged dormancy. Functional experiments confirmed that GA promotes floral bud growth, while ABA and its inhibitors modulate dormancy duration. Additionally, CsAPETALA1 (CsAP1) was identified as a target of ABA, influencing floral bud activation and development. These findings suggest a complex interplay between GA and ABA in orchestrating the floral transition, providing valuable insights for horticultural practices.
Dr. Fengxi Yang, the lead researcher, emphasized the significance of their findings, "Understanding the hormonal regulation of floral development in Chinese Cymbidium orchids offers new perspectives on managing flowering cycles in ornamental plants. Our study highlights the antagonistic roles of gibberellin and abscisic acid in bud dormancy and activation, which could lead to innovative approaches in horticulture. By manipulating these hormones, we can potentially enhance flowering efficiency and quality in various orchid species, benefiting both commercial cultivation and conservation efforts."
The insights gained from this study have significant implications for horticultural practices and commercial orchid cultivation. By understanding the hormonal control of flower development, growers can manipulate GA and ABA levels to optimize flowering times and improve floral quality. This knowledge can also aid in the development of new orchid varieties with desired blooming characteristics. Additionally, the study's findings contribute to broader botanical research, offering a framework for exploring hormonal interactions in other perennial plants, thus enhancing agricultural productivity and sustainability.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhae073
Funding information
This research was funded by grants from the National Natural Science Foundation of China (31872151, 31672184), the Guangzhou Science and Technology Project (201707010307), the Innovation Team of Modern Agriculture Industry Technology System in Guangdong Province (2021KJ121), and the Guangdong Academy of Agricultural Sciences Discipline Team Construction Project (202127TD, BZ202006, R2020PY-JX018).
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, 2022. 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.
Journal
Horticulture Research
Subject of Research
Not applicable
Article Title
Integrated proteomic, transcriptomic, and metabolomic profiling reveals that the gibberellin–abscisic acid hub runs flower development in the Chinese orchid Cymbidium sinense
Article Publication Date
12-Mar-2024
COI Statement
The authors declare that they have no competing interests.