Timing is everything: what tea plants teach us about light and productivity
image: Schematic illustration of the circadian clock that regulates the photosynthetic production of the tea plant.
Credit: Horticulture Research
Disruptions in daily light cycles can throw tea plants' internal rhythms into disarray—undermining their ability to photosynthesize efficiently. In a new study, researchers used a mathematical model and experimental validation to explore how constant light and skeleton photoperiods (6 hours light/6 dark or 3/3) interfere with the biological clock of tea plants. They found that both the timing and stability of key circadian and photosynthesis-related genes were affected, leading to changes in photosynthetic rates and stomatal behavior. These findings reveal how sensitive tea plants are to light rhythms and offer new insights into how subtle shifts in photoperiod can ripple through plant physiology.
Circadian rhythms help plants align internal processes with external cycles of day and night. In crops, this timing system regulates everything from photosynthesis to flowering, directly impacting growth and yield. While well-studied in model plants like Arabidopsis, the circadian machinery in tea (Camellia sinensis)—a globally important crop—remains poorly understood. Tea plants rely on light not only for energy but also as a signal to trigger timely gene expression and development. However, with rising use of artificial lighting and the looming effects of climate change, irregular light cycles are becoming more common. Due to these challenges, it is necessary to investigate how photoperiod disturbances impact tea plant rhythms and performance.
In a study (DOI: 10.1093/hr/uhae226) published on August 8, 2024, in Horticulture Research, scientists from Nanjing Agricultural University have uncovered how skeleton photoperiods interfere with the circadian system and photosynthetic performance of tea plants. By combining gene expression analysis with a dynamic computational model, the team investigated how four different light regimes—including constant and fragmented light patterns—alter physiological rhythms. Their findings highlight the crucial role of synchronized internal clocks in sustaining tea plant health and productivity.
To investigate the effects of disrupted light cycles, the researchers exposed tea plants to four lighting conditions: normal (12 hours light/12 dark), constant light (24L), and two skeleton photoperiods (6L6D and 3L3D). They monitored the expression of circadian clock genes (CCA1, PRR9, TOC1, ELF4) and photosynthesis-related genes (Lhcb1, RbcS1, atpA) across time points and used differential equations to simulate the rhythmic gene behaviors. Constant light caused delays in gene expression peaks by 1–2 hours, while skeleton photoperiods induced unstable or shortened oscillations. These disturbances cascaded into reduced photosynthetic efficiency and irregular stomatal openings. The 3L3D condition, in particular, caused fragmented gene expression and unpredictable changes in transpiration and CO₂ uptake. The model accurately mirrored experimental outcomes, reinforcing the link between light rhythms and physiological performance in tea plants.
“Our study demonstrates how even small disruptions in light timing can destabilize the circadian system of tea plants,” said Dr. Jing Zhuang, senior author of the study. “By pairing mathematical modeling with gene expression data, we've shown how the internal clock governs photosynthesis and stomatal control. This work not only deepens our understanding of tea plant physiology but also opens new pathways for precision agriculture—where managing light schedules could become a tool for boosting yield and resilience.”
These findings carry broad implications for the tea industry and beyond. In controlled environments such as greenhouses or plant factories, manipulating light regimes in harmony with circadian rhythms could enhance crop performance. The mathematical model developed in this study could serve as a predictive tool to optimize lighting strategies or assess plant responses to stress. Future work will extend these experiments to longer or seasonally realistic light cycles, as well as to different light colors. Ultimately, understanding and harnessing the circadian clock may pave the way for new breeding strategies and agricultural practices—enabling crops like tea to thrive in a changing world.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhae226
Funding information
The research was supported by the National Natural Science Foundation of China (31870681), the Provincial Policy Guidance Program North Jiangsu Science and Technology Special Project (SZ-LYG202126), Collection and Creation of Horticultural Crop Germplasm Resources of Jiangsu (JSFEM-202212), and the Priority Academic Program Development of Jiangsu Higher Education Institutions Project (PAPD).
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.