A new study has identified a crucial genetic mechanism that controls caffeine production in tea plants, potentially paving the way for creating tea varieties with customized caffeine levels to meet different consumer preferences.

Researchers from Hunan Agricultural University and the United States Department of Agriculture have uncovered how a specific gene called CsbHLH1 works together with a molecule called miR1446a to regulate caffeine production in tea plants. The findings were published on December 29, 2023, in Horticulture Research.

The research team analyzed various tea plant varieties using advanced techniques such as liquid chromatography-mass spectrometry and genetic analysis. They found that CsbHLH1 acts as a natural brake on caffeine production by suppressing another gene called TCS1, which is responsible for making caffeine.

“Our findings represent a significant leap forward in understanding the molecular regulation of caffeine in tea plants,” said Dr. Zhonghua Liu, the study’s lead researcher. “This could fundamentally change tea cultivation practices and lead to the development of new varieties that cater to specific consumer demands.”

The study focused on several tea varieties, including one known as ‘Jianghua Kucha’ which naturally produces higher levels of caffeine than other varieties. By comparing these different plants, the researchers were able to understand how genetic differences lead to varying caffeine levels.

One of the study’s key discoveries was how a small molecular component called miR1446a influences caffeine production. This molecule can reduce the activity of the CsbHLH1 gene, which in turn allows more caffeine to be produced. This creates a precise control system that tea plants use to regulate their caffeine levels.

The implications of this research extend beyond the laboratory. Tea producers could potentially use this knowledge to develop new varieties of tea with precisely controlled caffeine levels. This could lead to the creation of naturally low-caffeine teas for evening consumption or higher-caffeine varieties for morning beverages.

The researchers used multiple approaches to verify their findings, including analyzing tea plants where they temporarily blocked the CsbHLH1 gene’s function. When they did this, the plants produced more caffeine, confirming the gene’s role in regulating caffeine production.

While the study represents a significant advance in understanding how tea plants produce caffeine, the researchers note that several questions remain unanswered. They still need to investigate how this newly discovered genetic mechanism interacts with other factors that influence caffeine production in tea plants.

The research was supported by various organizations, including the Natural Science Foundation of Hunan Province and the National Natural Science Foundation of China, highlighting the collaborative nature of this scientific discovery.