The CsmiR397a-CsLAC17 module regulates lignin biosynthesis to balance the tenderness and gray blight resistance in young tea shoots

Abstract

Lignin accumulation can enhance the disease resistance of young tea shoots (Camellia sinensis). It also greatly reduces their tenderness, which indirectly affects the quality and yield of tea. Therefore, the regulation of lignin biosynthesis appears to be an effective way to balance tenderness and disease resistance in young tea shoots. In this study, we identified a laccase gene, CsLAC17, that is induced during tenderness reduction and gray blight infection in young tea shoots. Overexpression of CsLAC17 significantly increased the lignin content in transgenic Arabidopsis, enhancing their resistance to gray blight and decreasing stem tenderness. In addition, we found that CsLAC17 was negatively regulated by the upstream CsmiR397a by 5′-RLM-RACE, dual-luciferase assay, and transient expression in young tea shoots. Interestingly, the expression of CsmiR397a was inhibited during tenderness reduction and gray blight infection of young tea shoots. Overexpression of CsmiR397a reduced lignin accumulation, resulting in decreased resistance to gray blight and increased stem tenderness in transgenic Arabidopsis. Furthermore, the transient overexpression of CsmiR397a and CsLAC17 in tea leaves directly confirms the function of the CsmiR397a-CsLAC17 module in lignin biosynthesis and its effect on disease resistance. These results suggest that the CsmiR397a-CsLAC17 module is involved in balancing tenderness and gray blight resistance in young tea shoots by regulating lignin biosynthesis.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 31902071), the Key Research and Development Program of Shaanxi (No. 2022NY-154), and the China Agricultural Research System of Ministry of Finance and Ministry of Agriculture and Rural Affairs (CARS-19). We sincerely thank Dr Yangyang Yuan (Horticulture Science Research Center at College of Horticulture, NWAFU) for their technical support in this work.

Author contributions

W.W., Y.Y., and S.L. conceived and designed the experiments; H.Y., X.J., and T.G. performed the experiments; H.Y., S.G, L.X., and P.Z. analysed the data; H.Y. and Y.Q. wrote the paper; W.W., Y.Y., and S.L. participated in the paper revision.

Data availability

All relevant data can be found within the paper and its supporting materials.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Supplementary data

Supplementary data is available at Horticulture Research online.

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