Spring cold stress at high altitudes in southeastern Xizang activates CsABF2 to regulate chlorophyll degradation and phenolic biosynthesis in tea plants

Abstract

The tea plant (Camellia sinensis), native to warm and humid low-latitude regions of southwestern China, has expanded to higher altitudes, including southeastern Xizang, where cultivation above 2500 m poses challenges due to low accumulated temperatures. However, the impact of high-altitude climatic conditions, particularly temperature, on tea growth remains underexplored. To investigate, weather stations were deployed at three altitudes in southeastern Xizang to monitor spring temperature fluctuations: Medog (MD, 1200 m), Zayü (ZY, 1720 m), and Layue in Bayi District (BY, 2600 m). Field observations and meteorological data indicated that the milder spring temperatures in MD and ZY facilitated normal budburst and growth, whereas the lower temperatures in BY delayed budburst and resulted in leaf yellowing and browning. Comparative experiments revealed that seedlings exposed to fluctuating low temperatures (10°C/4°C) experienced the most severe cold injury and exhibited the lowest germination rates compared to seedlings under constant-temperature treatments. Transcriptome analysis uncovered differential expression of genes involved in chlorophyll degradation, lignin biosynthesis, and flavonoid pathways under cold stress. Functional characterization of the cold-induced transcription factor CsABF2 revealed its central role in activating these pathways, as evidenced by antisense oligodeoxynucleotide (AsODN) silencing and promoter activation assays, to activate key downstream genes: CsSGR1 (chlorophyll degradation), CsPALa (phenylpropanoid pathway), and CsMYB6c (flavonoid biosynthesis). These results provide mechanistic insights into how spring temperature variability at high altitudes impairs tea plant development and alters quality-related metabolites, offering a molecular basis for improving cold resilience in tea cultivation.

Acknowledgments

This work was financially supported by the joint funds of National Natural Science Foundation of China (U21A200416), the Natural Science Foundation of China (32372756, 32372760), and the National Key Research and Development Program of China (2022YFF1003103).

Authors contributions

Yipeng Huang drafted the manuscript. Yipeng Huang, Didi Jin, and Tianming Jiao conducted the experiments and performed the data analysis. Zhenhong Wang, Zhao Lei, Didi Jin, and Yipeng Huang collected samples and provided the necessary experimental materials. Ting Jiang, Xiaolan Jiang, and Haiyan Wang supplied the reagents and analytical tools. Tao Xia, Liping Gao, and Yunsheng Wang supervised the experimental design. Lastly, Yajun Liu revised the manuscript. All authors have read and approved the final version of the manuscript.

Data availability

The raw sequencing data from this study have been deposited in the Genome Sequence Archive in BIG Data Center (https://ngdc.cncb.ac.cn/), Beijing Institute of Genomics (BIG), Chinese Academy of Sciences, under the accession number CRA026368 and CRA023112. All relevant data can be found within the manuscript and its supporting materials. Further data are available from the corresponding authors.

Conflicts of interest statement

The authors declare no competing interests.

Supplementary material

Supplementary material is available at Horticulture Research online.

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