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.

中文翻译：

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两种富含亮氨酸的重复受体样激酶在茶树中启动食草防御反应


富含亮氨酸的重复受体样激酶 （LRR-RLK） 已成为食草感知和随后防御启动的关键调节因子。虽然它们在草本植物中的功能已逐渐阐明，但与食草相关的 LRR-RLKs 在木本植物中的作用在很大程度上仍然未知。在本研究中，我们挖掘了茶树 （Camellia sinensis） 的基因组和转录组数据，共鉴定出 307 个 CsLRR-RLK 成员。系统发育分析将这些 CsLRR-RLKs 及其拟南芥同源物分为 14 个亚组。基因结构和保守结构域分析揭示了亚组成员之间的显着相似性。在鉴定的 CsLRR-RLKs 中，我们专注于两种质膜定位的 LRR-RLK，CsLRR-RLK44 和 CsLRR-RLK239，它们彼此之间不形成同型二聚体或异二聚体。两者都对食草动物反应强烈，它们的表达模式与不同茶种质中的食草动物抗性表型显著相关。CsLRR-RLK44 和 CsLRR-RLK239 在丝裂原活化蛋白激酶 （MPK） 级联反应的上游起作用，并调节防御相关 MPK 和 WRKY 转录因子的表达。此外，沉默 CsLRR-RLK44 或 CsLRR-RLK239 降低了食草诱导的茉莉酸盐的水平，从而削弱了植物对茶几何幼虫 （Ectropis obliqua） 的抵抗力。我们的工作首次证明，在木本植物中，LRR-RLKs 对于通过激活规范信号传导（包括 MPK、WRKYs 和茉莉酸盐）增强食草动物的抵抗力至关重要。此外，我们的研究扩展了对 LRR-RLKs 如何从草到具有重要经济意义的树种启动植物防御的机制见解。