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Journal of Tea Science ›› 2025, Vol. 45 ›› Issue (5): 742-756.

• Research Paper • Previous Articles     Next Articles

Identification of CsDET2 and Its Response Analysis to Photoperiod and Abiotic Stress in Camellia sinensis

LI Guinan1, YANG Ni1, LUO Wei1, ZHANG Jiaqi1, HU Zhihang1, XIONG Aisheng2, HAO Jiannan1, ZHUANG Jing1,*   

  1. 1. Tea Research Institution, Ministry of Agriculture and Rural Affair Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, College of Horticulture, Nanjing Agricultural University, Nanjing 211800, China;
    2. State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing 211800, China
  • Received:2025-03-05 Revised:2025-07-09 Online:2025-10-15 Published:2025-10-17

Abstract: Tea plants [Camellia sinensis (L.) O. Kuntze] is important leaf cash crops in China, and its growth and development are affected by plant hormones. As one of the six classical plant hormones, brassinosteroids (BRs) play crucial roles in regulating both developmental processes and stress adaptation in tea plants. Steroid 5α-reductase is a key enzyme in the brassinosteroid biosynthesis pathway. To characterize steroid 5α-reductase in Camellia sinensis, the CsDET2 gene was cloned from tea cultivar ‘Shuchazao'. Then, the physicochemical properties, secondary and tertiary structures, sequence characteristics, phylogenetic relationships, and subcellular localization of the encoded protein were analyzed, along with the cis-acting elements in gene promoter region. Furthermore, the expression profile of CsDET2 was examined across different organs under abiotic stress conditions and during a 12 h/12 h photoperiod cycle. The results reveal that the CsDET2 gene contains a 783 bp open reading frame encoding 260 amino acids. The CsDET2 protein has a molecular weight of 30 158.97 Da with a theoretical isoelectric point of 9.28, and is predominantly composed of α-helices and random coils, containing a characteristic steroid dehydrogenase domain. Comparative sequence alignment with DET2 proteins from 15 species shows 78.25% amino acid sequence identity. Phylogenetic analysis suggests that CsDET2 shares the closest evolutionary relationship with AfDET2 from Actinidiarufa. Subcellular localization experiments confirm that CsDET2 is localized in the cytoplasm. Analysis of cis-acting elements reveals that the promoter region of CsDET2 contains 4 types of photo-responsive elements, 4 types of stress-responsive elements, 3 types of hormone responsive elements, and 5 types of transcription factor binding sites. The fluorescence quantification results show that CsDET2 was expressed in all organs, and the expression level was the highest in the old leaves. In the 12L/12D photoperiod, the expression level of CsDET2 decreased first and then increased during the daytime, increased first and then decreased at night, and the expression level of CsDET2 at night was higher than that during the daytime. The expression of CsDET2 shows significant changes under high temperature and salt stress treatments, and was regulated by exogenous gibberellins. The results provided a theoretical basis and valuable insights for further exploring the function of tea plant steroid 5α-reductase.

Key words: Camellia sinensis, brassinosteroids, bioinformatics analysis, photoperiod, abiotic stress

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