Free amino acids (FAAs) positively determine the tea quality, notably theanine, endowing umami taste of tea infusion. However, their concentrations vary significantly across different tea varieties, affecting both the flavor and nutritional profile of the tea. In new research led by the Tea Research Institute of the Chinese Academy of Agricultural Sciences and Huazhong Agricultural University, 339 tea accessions were collected to study FAA levels for deciphering their variation and accumulation mechanism. The results offer insights and benefits for the conservation, evaluation, and utilization of tea germplasms, achieving the ultimate goal of tea plants’ genetic improvement and breeding, and provide valuable information and approaches for further deciphering complex composite traits in tea plants.
By analyzing the variation of FAAs among 339 tea accessions in two years, we can know that the determined components of FAAs including arginine, glutamine, glutamate, alanine, and theanine with the highest diversity index differed among different genetic resources and intraspecific accessions. Meanwhile, their amounts in Camellia sinensis were all significantly higher than in the wild relatives. The study confirmed the significant opposite trend between chlorophyll and FAA profiles. Image credit: Sci.News.
“Tea plant (Camellia sinensis) and its wild relatives, evergreen and woody perennial trees, belong to the genus Camellia of the family Theaceae with a long history of cultivation,” said co-senior author Dr. Liang Chen from the Tea Research Institute and colleagues.
“They have been becoming the most important non-alcoholic beverages following wide consumption worldwide that originated in southwestern China.”
“For commercial and quality value, the secondary metabolites in tea plants are the vital criteria related to pleasant flavors, nutritional value, and numerous health benefits, encompassing polyphenols, catechins, caffeine, theanine, and terpenes.”
“Therefore, the evaluation and utilization of tea accessions are fundamentally important for us contributing to the facilitation of the excavation and breeding of new cultivars.”
“Among them, the distinctive tea cultivars such as albino, purple, and other variations possess a unique quality devoting the formation and accumulation of valuable secondary metabolites to their function.”
“A higher concentration of theanine content in albino tea cultivars, which exhibit abundant white and yellowing tender leaves, contributes to the umami taste of tea fusion but also prevents people from developing various unhealthy conditions including obesity, inflammation, and aging.”
In the study, the researchers conducted a detailed investigation of 339 tea accessions to unravel the genetic and metabolic factors influencing the variation and accumulation of FAAs, with a particular focus on theanine.
They discovered that cultivated tea varieties exhibited higher levels of theanine compared to wild relatives, pointing to a genetic enrichment associated with domestication.
Alanine and theanine showed the highest diversity index, underlining their critical role in shaping tea’s quality.
The scientists also identified phytochrome interacting factor 1 (CsPIF1) as a key negative regulator of theanine content.
When CsPIF1 was transiently knocked down in tea plants, theanine levels increased significantly, a result confirmed in the model plant Arabidopsis.
This discovery paves the way for future research on gene editing techniques aimed at controlling theanine biosynthesis, transport, and hydrolysis, offering new opportunities to improve tea quality through genetic manipulation.
“Our research not only enhances the understanding of the genetic makeup of tea but also opens up new avenues for targeted breeding efforts,” Dr. Chen said.
“By manipulating the expression of CsPIF1 and related genes, we can potentially increase theanine levels, directly impacting the nutritional and sensory properties of tea.”
“This insight could be transformative for the tea industry, offering breeders the tools to fine-tune flavor and enhance the health benefits of tea through genetic interventions.”
The findings appear in the journal Horticulture Research.
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Rong Huang et al. 2024. Comprehensive dissection of variation and accumulation of free amino acids in tea accessions. Horticulture Research 11 (1): uhad263; doi: 10.1093/hr/uhad263
Source : Breaking Science News