Temperature and Hormone Tweaks Give Scientists a Dial to Turn Bulb Dormancy On and Off

Every summer, farmers in Zhejiang Province, China, face a quiet crisis buried in the soil. Fritillaria thunbergii, a prized traditional Chinese medicinal herb whose bulbs contain pharmacologically valuable alkaloids, spends the hot months in a state of enforced dormancy. Under conventional open-air storage, the sustained warmth of the growing season—soil temperatures that routinely hover between 20 and 25 degrees Celsius for stretches of 60 to 90 days—takes a heavy toll: between 15 and 20 percent of bulbs rot each year before they can be replanted. A new study published in BMC Plant Biology reports that this seemingly fixed seasonal rhythm can be manipulated with surprising precision, using nothing more exotic than temperature control and well-understood plant growth regulators.

The research, led by Pan Wang and colleagues at the Zhejiang Academy of Agricultural Sciences together with collaborators at Zhejiang Chinese Medical University and Hangzhou Normal University, tackles a problem that has long frustrated growers of bulbous crops. The industry faces two demands that pull in opposite directions. Breeders want dormancy to end as quickly as possible, so that generations can be cycled faster and new varieties selected more efficiently. Storage managers, by contrast, want dormancy to last as long as possible, so that bulbs survive the summer intact rather than sprouting prematurely or decaying. A single-temperature strategy cannot serve both goals at once, which is why the team turned to a combined approach pairing temperature gradients with gibberellin chemistry.

Gibberellins are a family of plant hormones best known for triggering germination, stem elongation, and the breaking of seed and bud dormancy. Their antagonists are equally important: abscisic acid, or ABA, is the hormone that establishes and maintains dormancy in the first place. The balance between these two signaling systems—often summarized as the GA-to-ABA ratio—acts as a molecular switch governing whether a dormant organ stays asleep or wakes up. The researchers reasoned that if they could steer this ratio pharmacologically while simultaneously controlling the thermal environment, they could push the switch in either direction at will.

To test this, the team treated F. thunbergii bulbs with gibberellic acid, the biologically active hormone GA3, and with a cocktail of gibberellin biosynthesis inhibitors. The inhibitors included uniconazole, chlormequat chloride, and prohexadione-calcium, three compounds widely used in agriculture to block the enzymatic steps that produce active gibberellins inside plant tissues. Bulbs received these treatments across a range of temperature conditions, and the researchers then tracked what happened over time using three complementary lines of evidence: visible phenotypic changes such as sprouting, targeted hormone profiling by liquid chromatography–mass spectrometry, and transcriptome sequencing to capture which genes were switched on or off as dormancy shifted.

The results were striking in both directions. When bulbs were held at 15 degrees Celsius and treated with GA3, dormancy broke in roughly 43.7 days—a rapid release that would allow breeders to compress generation times substantially. At the same 15-degree temperature, but with the inhibitor mixture instead of the hormone, dormancy was stretched to more than 103.4 days, more than doubling the dormant window and offering a plausible route to safer over-summering storage. In other words, the same temperature became either an accelerant or a preservative depending entirely on which way the gibberellin pathway was pushed.

Underneath these phenotypes, the molecular measurements told a coherent story. The hormone profiling confirmed that the treatments worked by shifting the endogenous GA3-to-ABA ratio, tilting the internal chemical environment toward either growth or dormancy maintenance. The transcriptomic analysis went further, identifying differentially expressed genes and organizing them through weighted gene co-expression network analysis, a computational method that groups genes whose activity patterns rise and fall together. These networks revealed that the treatments did not merely alter hormone levels; they reprogrammed carbohydrate metabolism pathways, rewiring how the bulb mobilized and allocated its stored sugars as it transitioned between dormant and active states.

This coupling of hormone signaling with carbohydrate metabolism makes physiological sense. A bulb is essentially an underground storage organ, packed with starch and other reserves that must be converted into soluble sugars to fuel new shoot growth when dormancy ends. Blocking gibberellin synthesis appears to keep those mobilization programs suppressed, holding the bulb in a metabolically conservative state that resists both sprouting and the decay organisms that exploit active tissues. Conversely, supplying GA3 at a cool 15 degrees seems to coordinate the hormonal trigger with the metabolic machinery needed to break dormancy cleanly and quickly, rather than letting warm temperatures drive a slow, uneven, and rot-prone emergence.

Why does the temperature component matter at all if the hormone does the heavy lifting? The study’s design suggests that 15 degrees Celsius occupies a favorable middle ground for F. thunbergii: cool enough to slow the metabolic deterioration and microbial growth that plague bulbs stored in the 20-to-25-degree range of Zhejiang summers, yet warm enough for the hormonal signals to be perceived and executed. Temperature and gibberellin signaling are known to interact in plant dormancy regulation more broadly, and the synergistic effects observed here—where neither temperature alone nor hormone treatment alone could achieve the same bidirectional control—support the idea that the two inputs converge on shared downstream gene networks.

The practical implications extend beyond one medicinal species. Fritillaria thunbergii is a useful model for the broader class of geophytes—bulbs, corms, and tubers—whose life cycles are governed by seasonal dormancy and whose value depends on surviving the interval between growth phases. The demonstration that a simple, inexpensive combination of temperature setpoints and commercially available gibberellin modulators can extend or shorten dormancy by more than 60 days offers a template that could be adapted to other crops facing similar summer storage losses or breeding bottlenecks. For an industry losing up to a fifth of its bulbs annually, even partial adoption of such a protocol could translate into meaningful economic and resource savings.

There are, of course, steps between a controlled experiment and a field-ready protocol. The study, published open access on 6 October 2026, was conducted under defined laboratory conditions with targeted treatments, and scaling the approach will require validation across commercial storage facilities, diverse bulb sizes, and multiple growing seasons. The authors also note that their work was supported by regional Chinese medicine industry programs in Zhejiang Province, reflecting local investment in solving a problem specific to the herb’s main production area. Still, the conceptual advance is clear: dormancy in this species is not an immovable seasonal fact but a tunable physiological state, governed by a GA-to-ABA switch and its downstream metabolic networks, that growers can now adjust from both directions. For breeders racing to develop better varieties and for farmers trying to keep bulbs alive through the heat, that dial may prove to be the most valuable harvest of all.

Subject of Research: Temperature and gibberellin regulation of summer bulb dormancy in Fritillaria thunbergii

Article Title: Physiological and transcriptomic mechanisms of summer dormancy regulation in F. thunbergii bulbs synergistically induced by temperature and gibberellin modulators

Article References: Wang, P., Cai, L., Sun, J., Li, H., Sui, N., Lu, P., Shen, Y., Lu, J., Sun, C., & Wang, Z. (2026). Physiological and transcriptomic mechanisms of summer dormancy regulation in F. thunbergii bulbs synergistically induced by temperature and gibberellin modulators. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10082-y

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10082-y

Keywords: Fritillaria thunbergii, summer dormancy, gibberellic acid, abscisic acid, gibberellin inhibitors, temperature regulation, bulb storage, transcriptomics, WGCNA, carbohydrate metabolism, medicinal plants, plant hormones