Two leucine-rich repeat receptor-like kinases initiate herbivory defense responses in tea plants

Abstract

Leucine-rich repeat receptor-like kinases (LRR-RLKs) have emerged as key regulators of herbivory perception and subsequent defense initiation. While their functions in grass plants have been gradually elucidated, the roles of herbivory-related LRR-RLKs in woody plants remain largely unknown. In this study, we mined the genomic and transcriptomic data of tea plants (Camellia sinensis) and identified a total of 307 CsLRR-RLK members. Phylogenetic analysis grouped these CsLRR-RLKs into 14 subgroups along with their Arabidopsis homologs. Gene structure and conserved domain analyses revealed notable similarities among subgroup members. Among the identified CsLRR-RLKs, we focused on two plasma membrane-localized LRR-RLKs, CsLRR-RLK44, and CsLRR-RLK239, which do not form homodimers or heterodimers with each other. Both respond strongly to herbivory, and their expression patterns significantly correlate with herbivore resistance phenotypes across different tea accessions. CsLRR-RLK44 and CsLRR-RLK239 act upstream of mitogen-activated protein kinase (MPK) cascades and modulate the expression of defense-related MPKs and WRKY transcription factors. Additionally, silencing CsLRR-RLK44 or CsLRR-RLK239 reduced the levels of herbivory-induced jasmonates, thereby weakening the plant resistance to tea geometrid larvae (Ectropis obliqua). Our work is the first to demonstrate that in woody plants, LRR-RLKs are essential for enhancing herbivore resistance through the activation of the canonical signaling, including MPKs, WRKYs, and jasmonates. Furthermore, our study extends mechanistic insights into how LRR-RLKs initiate plant defenses from grasses to economically important tree species.

Acknowledgements

We thank Prof. Dr. Xinchao Wang for kindly supplying experimental materials. This research was funded by National Natural Science Foundation of China (32372775), Central Public-interest Scientific Institution Basal Research Fund (Y2023PT03), the Zhejiang Science and Technology Major Program on Agricultural New Variety Breeding-Tea Plant (2021C02067), and the Elite Youth Program of Chinese Academy of Agricultural Sciences.

Author contributions

M.Y. and J.H. conceived the research; M.Y., J.H., and J.Z. designed the experiments; Q.J., C.D., L.F., Z.W., Y.L., L.H., C.L., L.W., and M.Y. performed experiments; M.Y. and Q.J. analyzed the data and wrote the first draft. All authors read and approved the article.

Data availability

The data that support the findings of this study are available in the article and the Supplementary Information.

Conflict of interests

No conflict of interests declared.

Supplementary data

Supplementary data is available at Horticulture Research online.

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