Anther development is one of the most delicate stages of flower formation, controlling whether a plant can produce viable pollen. Hormones called gibberellins (GAs) are key regulators of this process, influencing cell division, expansion, and tapetal cell degradation. Yet, both too much and too little GA can trigger pollen sterility. Previous research identified LoMYB65, a GA-responsive transcription factor, as vital for lily pollen development. However, how GA signaling communicates with its own biosynthesis machinery in this context remained poorly understood. Due to these challenges, it is necessary to explore the molecular network that stabilizes GA homeostasis and ensures normal anther development in lilies.
A research team from Nanjing Agricultural University and Beijing Forestry University has uncovered a genetic feedback loop that stabilizes hormone levels during lily pollen formation. The study (DOI: 10.1093/hr/uhae339), published on March 1, 2025, in Horticulture Research, identifies LoBLH6 as a crucial partner of LoMYB65. Together, they form a hormonal control system that fine-tunes gibberellin synthesis, preventing reproductive disorders and ensuring the formation of fertile pollen grains.
Through a combination of genetic, biochemical, and microscopic analyses, the team found that LoBLH6, a BEL1-like homeodomain transcription factor, directly binds to LoMYB65 via its BELL domain, forming a regulatory complex. Both genes are coexpressed in the tapetum and microspores—the key tissues driving pollen maturation. When LoBLH6 expression was silenced, lilies exhibited abnormal anther structures, reduced pollen quantity, and poor germination, all accompanied by excessive gibberellin accumulation. Remarkably, external GA treatment reproduced these defects, confirming that hormone imbalance disrupts pollen development. Further experiments showed that LoBLH6 binds to the promoter of LoGA20ox1, a pivotal enzyme gene in gibberellin biosynthesis, and represses its activity. The repression became stronger when LoMYB65 was coexpressed, and the interaction between the two proteins intensified under GA treatment. This establishes a self-regulating feedback loop where the LoBLH6–LoMYB65 complex dampens GA production once levels rise, preserving the delicate hormonal balance required for healthy anther and pollen formation.
“Flower fertility is all about balance,” said Professor Nianjun Teng, corresponding author of the study. “Our discovery shows how lilies prevent hormonal chaos from sabotaging pollen formation. The LoBLH6–LoMYB65 module acts as a safeguard, ensuring that gibberellin levels remain within the optimal range. It bridges hormone biosynthesis and signaling into a single feedback mechanism—something that has long been hypothesized but rarely demonstrated in flowering plants.”
The findings provide a valuable genetic tool for horticultural breeding and reproductive regulation. By manipulating LoBLH6 activity, breeders could develop pollenless lily varieties that maintain ornamental value while reducing pollen contamination and allergenic risks. Moreover, the discovery highlights a universal principle of hormonal balance that may extend to other crops, offering strategies to enhance fertility, seed quality, and yield stability under stress. The LoBLH6–LoMYB65–GA20ox1 feedback circuit thus represents a promising target for future biotechnological applications aimed at precise control of plant growth and reproduction.
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References
DOI
10.1093/hr/uhae339
Original Source URL
https://doi.org/10.1093/hr/uhae339
Funding information
This research was supported by the National Key Research and Development Program of China (2022YFD1200500), the `JBGS' Project of Seed Industry Revitalization in Jiangsu Province (JBGS[2021]093), and the Project for Crop Germplasm Resources Conservation of Jiangsu Province (2021-SJ-011).
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.