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Lin S, Chen Z, Chen T, Deng W, Wan X, Zhang Z. Theanine metabolism and transport in tea plants ( Camellia sinensis L.): advances and perspectives. Crit Rev Biotechnol 2022; 43:327-341. [PMID: 35430936 DOI: 10.1080/07388551.2022.2036692] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Theanine, a tea plant-specific non-proteinogenic amino acid, is the most abundant free amino acid in tea leaves. It is also one of the most important quality components of tea because it endows the "umami" taste, relaxation-promoting, and many other health benefits of tea infusion. Its content in tea leaves is directly correlated with the quality and price of green tea. Theanine biosynthesis primarily occurs in roots and is transported to new shoots in tea plants. Recently, great advances have been made in theanine metabolism and transport in tea plants. Along with the deciphering of the genomic sequences of tea plants, new genes in theanine metabolic pathway were discovered and functionally characterized. Theanine transporters were identified and were characterized on the affinity for: theanine, substrate specificity, spatiotemporal expression, and the role in theanine root-to-shoot transport. The mechanisms underlying the regulation of theanine accumulation by: cultivars, seasons, nutrients, and environmental factors are also being rapidly uncovered. Transcription factors were identified to be critical regulators of theanine biosynthesis. In this review, we summarize the progresses in theanine: biosynthesis, catabolism, and transport processes. We also discuss the future studies on theanine in tea plants, and application of the knowledge to crops to synthesize theanine to improve the health-promoting quality of non-tea crops.
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Affiliation(s)
- Shijia Lin
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
| | - Ziping Chen
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
| | - Tingting Chen
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
| | - Weiwei Deng
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
| | - Xiaochun Wan
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
| | - Zhaoliang Zhang
- State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, PR China
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She G, Yu S, Li Z, Peng A, Li P, Li Y, Chang M, Liu L, Chen Q, Shi C, Sun J, Zhao J, Wan X. Characterization of CsTSI in the Biosynthesis of Theanine in Tea Plants ( Camellia sinensis). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:826-836. [PMID: 35029385 DOI: 10.1021/acs.jafc.1c04816] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Theanine is a unique major amino acid in tea plants responsible for umami taste and mental health benefits of tea. However, theanine biosynthesis and physiological role in tea plants are not fully understood. Here, we demonstrate that tea plant theanine synthetase is encoded by a glutamine synthetase gene CsTSI. The expression pattern of CsTSI is closely correlated with theanine and glutamine levels in various tissues. CsTSI transcripts were accumulated in root tip epidermal cells, pericycle and procambial cells, where CsTSI presents as a cytosolic protein. Ectopic expression of the gene in Arabidopsis led to greater glutamine and theanine production than controls when fed with ethylamine (EA). RNAi knockdown or overexpression of CsTSI in tea plant hairy roots reduced or enhanced theanine and glutamine contents, respectively, compared with controls. The CsTSI recombinant enzymes used glutamate as an acceptor and ammonium or EA as a donor to synthesize glutamine and theanine, respectively. CsTSI expression in tea roots responded to nitrogen supply and deprivation and was correlated with theanine contents. This study provides fresh insights into the molecular basis for the biosynthesis of theanine, which may facilitate the breeding of high-theanine tea plants for improving the nutritional benefit of tea.
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Affiliation(s)
- Guangbiao She
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Shuwei Yu
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Zhenguo Li
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Anqi Peng
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Penghui Li
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Yingying Li
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Manman Chang
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Linlin Liu
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Qi Chen
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Chengying Shi
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Jun Sun
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Jian Zhao
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
| | - Xiaochun Wan
- State Key Laboratory of Tea Plant Biology and Utilization, College of Tea and Food Science & Technology, Anhui Agricultural University, Hefei 230036, China
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Fu X, Liao Y, Cheng S, Deng R, Yang Z. Stable Isotope-Labeled Precursor Tracing Reveals that l-Alanine is Converted to l-Theanine via l-Glutamate not Ethylamine in Tea Plants In Vivo. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:15354-15361. [PMID: 34904439 DOI: 10.1021/acs.jafc.1c06660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Tea plants (Camellia sinensis) specifically produce l-theanine, which contributes to tea function and taste. Ethylamine is a limiting factor differentiating l-theanine accumulation between tea and other plants. Ethylamine has long been assumed to be derived from l-alanine in tea. In this study, the l-alanine content in tea root cells was mainly located in vacuoles and mitochondria using a nonaqueous fractionation technique, while alanine decarboxylase in tea (CsADC) was located in the cytoplasm. Although CsADC was able to catalyze l-alanine decarboxylation to produce ethylamine in vitro, it may not provide the same enzyme activity in tea plants. Stable isotope-labeled precursor tracing in tea plants discovered that l-alanine is not a direct precursor of ethylamine but a precursor of l-glutamate, which is involved in l-theanine biosynthesis in tea. Cortex with epidermis from root tissue was the main location of ethylamine. In summary, l-alanine is converted to l-theanine via l-glutamate not ethylamine in tea plants in vivo.
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Affiliation(s)
- Xiumin Fu
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
| | - Yinyin Liao
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
| | - Sihua Cheng
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
| | - Rufang Deng
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
| | - Ziyin Yang
- Guangdong Provincial Key Laboratory of Applied Botany & Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, South China Botanical Garden, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
- University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China
- Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, No. 723 Xingke Road, Tianhe District, Guangzhou 510650, China
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