Leucine-rich repeat receptor-like kinases (LRR-RLKs) are ubiquitous in higher plants, which act as receptors of extracellular signals to trigger multiple physiological processes. However, the functions of the majority of LRR-RLKs remain largely unknown, especially in tomato (Solanum lycopersicum L.). Here, we found that MRK1 (Multiple resistance-associated kinase 1), encoding a novel tomato LRR-RLK, was significantly induced either by temperature stresses or bacterial pathogen attacks. Knocking out MRK1 impaired the tolerance to both cold and heat stress, accompanied with the decrease in transcripts of master regulators C-repeat binding factor 1 (CBF1) and Heat shock transcription factor a-1a (HsfA1a), respectively. Additionally, mrk1 mutants were hypersensitive to Pseudomonas syringae pv. tomato DC3000 and Ralstonia solanacearum and compromised pattern-triggered immunity (PTI) responses as evidenced by decreased reactive oxygen species production and reduced upregulation of the PTI marker genes. Moreover, bimolecular fluorescence complementation, split-luciferase assay and coimmunoprecipitation supported the existence of complex formation between the MRK1, FLS2 and Somatic embryogenesis receptor kinase (SERK3A/SERK3B) in a ligand-independent manner. This work demonstrates that tomato MRK1 as a novel positive regulator of multiple stresses, which might be a potential breeding target to improve crop stress resistance.

中文翻译：

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一种新的富含亮氨酸的重复受体样激酶 MRK1 调节番茄对多种压力的抗性。

富含亮氨酸的重复受体样激酶 (LRR-RLKs) 在高等植物中普遍存在，作为细胞外信号的受体来触发多种生理过程。然而，大多数 LRR-RLKs 的功能仍然很大程度上未知，尤其是在番茄 (Solanum lycopersicum L.) 中。在这里，我们发现编码新型番茄 LRR-RLK 的 MRK1（多重抗性相关激酶 1）受到温度胁迫或细菌病原体攻击的显着诱导。敲除 MRK1 会降低对冷应激和热应激的耐受性，同时主调控因子 C 重复结合因子 1 (CBF1) 和热休克转录因子 a-1a (HsfA1a) 的转录物分别减少。此外，mrk1 突变体对 Pseudomonas syringae pv 过敏。番茄 DC3000 和 Ralstonia solanacearum 和受损的模式触发免疫 (PTI) 反应，如活性氧产生减少和 PTI 标记基因上调减少所证明。此外，双分子荧光互补、分裂荧光素酶测定和免疫共沉淀支持 MRK1、FLS2 和体细胞胚胎发生受体激酶 (SERK3A/SERK3B) 之间以不依赖配体的方式形成复合物。这项工作表明，番茄 MRK1 作为一种新型的多重胁迫正调节因子，可能是提高作物抗逆性的潜在育种目标。分裂荧光素酶测定和免疫共沉淀支持 MRK1、FLS2 和体细胞胚胎发生受体激酶 (SERK3A/SERK3B) 之间以不依赖配体的方式形成复合物。这项工作表明，番茄 MRK1 作为一种新型的多重胁迫正调节因子，可能是提高作物抗逆性的潜在育种目标。分裂荧光素酶测定和免疫共沉淀支持 MRK1、FLS2 和体细胞胚胎发生受体激酶 (SERK3A/SERK3B) 之间以不依赖配体的方式形成复合物。这项工作表明，番茄 MRK1 作为一种新型的多重胁迫正调节因子，可能是提高作物抗逆性的潜在育种目标。