Hormone crosstalk sets the clock for lotus bud-break
image: In the present of ABA, two synergistic mechanisms collectively inhibit the lotus apical bud-break.
Credit: Horticulture Research
A research team has uncovered how two plant hormones work together to keep lotus buds dormant and determine when new growth begins. The study shows that abscisic acid (ABA) activates a molecular brake centered on the NnABI5 transcription factor, while jasmonic acid (JA) helps remove NnTIFY10A and NnTIFY10B proteins that normally restrain that brake. Once released, NnABI5 switches on dormancy-associated genes and suppresses apical bud-break. By mapping this hormone-controlled molecular circuit, the work offers a clearer explanation of how lotus coordinates seasonal growth and flowering, and identifies potential molecular targets for improving flowering-time management in ornamental and crop lotus without relying solely on environmental control.
Bud dormancy helps perennial plants survive unfavorable seasons, but the timing of bud-break also shapes later growth, flowering, and productivity. In lotus, spring bud emergence is closely associated with subsequent growth rate and flowering time, making dormancy control important for cultivation. Abscisic acid (ABA) is widely recognized as a dormancy-promoting hormone, whereas jasmonic acid (JA) participates in stress responses, development, and hormone crosstalk. Yet researchers have lacked direct evidence explaining how these two signals interact in lotus apical buds. In particular, the molecular link connecting ABA-responsive transcription factors, JA-pathway repressors, and downstream dormancy genes remained unresolved. Because of these challenges, an in-depth investigation of ABA–JA coordination during lotus apical bud-break was needed.
Led by researchers at the College of Horticulture and Sanya Research Institute of Nanjing Agricultural University, with collaborators from the Suzhou Academy of Agricultural Sciences, the Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, and the Xuzhou Academy of Agricultural Sciences, the study was published (DOI: 10.1093/hr/uhag125) on April 10, 2026, in Horticulture Research. The team examined how ABA and JA signaling converge on the NnTIFY10A/B–NnABI5 module to control the transition of lotus apical buds from dormancy to active growth.
Using the lotus cultivar ‘Aijiangnan’, the researchers treated dormant rhizome buds with ABA and tracked growth for seven and 14 days. After 14 days, untreated buds reached about 4.7 centimeters, while ABA-treated buds remained near 3.0 centimeters. Reverse transcription quantitative polymerase chain reaction (RT-qPCR), transient gene overexpression and silencing, and experiments in Arabidopsis thaliana showed that the NnABI5 gene encodes a basic leucine zipper (bZIP) transcription factor that suppresses bud-break and seed germination. NnABI5 directly activated the dormancy-related genes NnEM1 and NnEM6. Transiently increasing NnEM1 or NnEM6 slowed bud growth, while silencing either gene accelerated it, confirming that the downstream transcriptional cascade has a direct developmental effect. Yeast one-hybrid and two-hybrid tests, pull-down assays, bimolecular fluorescence complementation, electrophoretic mobility shift assays, and dual-luciferase analyses established the relevant protein interactions and promoter control. The Jasmonate ZIM-domain (JAZ) proteins NnTIFY10A and NnTIFY10B bound NnABI5 and weakened its ability to activate those targets. Overexpressing NnTIFY10A or NnTIFY10B accelerated lotus bud growth, whereas silencing them produced the opposite response. ABA also increased JA accumulation and the expression of JA-biosynthesis genes. Sodium diethyldithiocarbamate trihydrate (DIECA), a JA-biosynthesis inhibitor, partly relieved ABA-induced growth suppression. Protein-degradation tests further showed that ABA and JA promoted NnTIFY10A/B breakdown through the 26S proteasome pathway, freeing NnABI5 to reinforce dormancy.
The authors said the findings reveal a two-layer control system rather than a single hormonal switch. ABA directly strengthens the NnABI5–NnEM1/6 dormancy program and, at the same time, promotes the loss of NnTIFY10A/B proteins that would otherwise hold NnABI5 back. They said this arrangement helps explain how lotus buds convert changing hormone levels into a decisive developmental response. The model also places NnABI5 at a key junction between ABA and JA signaling, offering a mechanistic framework for studying how perennial plants balance winter survival with timely spring growth.
The results could guide future efforts to adjust lotus flowering schedules, improve synchronized bud emergence, and support more predictable ornamental and agricultural production. Rather than suggesting immediate hormone treatments for growers, the study identifies genes and protein interactions that could be explored through marker-assisted selection, molecular breeding, or carefully controlled growth-regulation strategies. The framework may also inform dormancy research in other perennial plants where ABA and JA signals overlap. However, the experiments were conducted mainly under controlled conditions and included transient transformation and heterologous tests. Field studies across cultivars and climates, together with direct tests of JA treatments and long-term effects, will be needed before the mechanism can be translated into practical cultivation tools.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhag125
Funding information
This research was funded by the funding of the National Natural Science Foundation of China (nos 31772346; 31971710; 32071829) and Jiangsu Agriculture Science and Technology Innovation Fund (CX(23)3138).
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.