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Article|02 Dec 2022|OPEN
Haem Oxygenase 1 is a potential target for creating etiolated/albino tea plants (Camellia sinensis) with high theanine accumulation
Ziping Chen1,2 ,† , Shijia Lin1 ,† , Tingting Chen1 , Mengxue Han1 , Tianyuan Yang1 , Yan Wang1 , Shilai Bao3,4 and Zhougao Shen1 , Xiaochun Wan1 , Zhaoliang Zhang,1 ,
1State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036, China
2Anhui Promotion Center for Technology Achievements Transfer, Anhui Academy of Science and Technology, Hefei, 230031, China
3State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
4School of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
*Corresponding author. E-mail:
Both authors contributed equally to the study.

Horticulture Research 10,
Article number: uhac269 (2023)
Views: 218

Received: 22 Sep 2022
Accepted: 01 Dec 2022
Published online: 02 Dec 2022


Theanine content is highly correlated with sensory quality and health benefits of tea infusion. The tender shoots of etiolated and albino tea plants contain higher theanine than the normal green tea plants and are valuable materials for high quality green tea processing. However, why these etiolated or albino tea plants can highly accumulate theanine is largely unknown. In this study, we observed an Arabidopsis etiolated mutant hy1–100 (mutation in Haem Oxygenase 1HO1) that accumulated higher levels of glutamine (an analog of theanine). We therefore identified CsHO1 in tea plants and found CsHO1 is conserved in amino acid sequences and subcellular localization with its homologs in other plants. Importantly, CsHO1 expression in the new shoots was much lower in an etiolated tea plants ‘Huangkui’ and an albino tea plant ‘Huangshan Baicha’ than that in normal green tea plants. The expression levels of CsHO1 were negatively correlated with theanine contents in these green, etiolated and albino shoots. Moreover, CsHO1 expression levels in various organs and different time points were also negatively correlated with theanine accumulation. The hy1–100 was hypersensitive to high levels of theanine and accumulated more theanine under theanine feeding, and these phenotypes were rescued by the expression of CsHO1 in this mutant. Transient knockdown CsHO1 expression in the new shoots of tea plant using antisense oligonucleotides (asODN) increased theanine accumulation. Collectively, these results demonstrated CsHO1 negatively regulates theanine accumulation in tea plants, and that low expression CsHO1 likely contributes to the theanine accumulation in etiolated/albino tea plants.