• The molecular mechanisms of quantitative resistance (QR) to fungal pathogens and their relationships with growth pathways are poorly understood.
• We identified tomato TRK1 (TPK1b Related Kinase1) and determined its functions in tomato QR and plant growth. TRK1 is a receptor-like cytoplasmic kinase that complexes with tomato LysM Receptor Kinase (SlLYK1). SlLYK1 and TRK1 are required for chitin-induced fungal resistance, accumulation of reactive oxygen species, and expression of immune response genes. Notably, TRK1 and SlLYK1 regulate SlMYC2, a major transcriptional regulator of jasmonic acid (JA) responses and fungal resistance, at transcriptional and post-transcriptional levels.
• Further, TRK1 is also required for maintenance of proper meristem growth, as revealed by the ectopic meristematic activity, enhanced branching, and altered floral structures in TRK1 RNAi plants. Consistently, TRK1 interacts with SlCLV1 and SlWUS, and TRK1 RNAi plants show increased expression of SlCLV3 and SlWUS in shoot apices. Interestingly, TRK1 suppresses chitin-induced gene expression in meristems but promotes expression of the same genes in leaves. SlCLV1 and TRK1 perform contrasting functions in defense but similar functions in plant growth.
• Overall, through molecular and biochemical interactions with critical regulators, TRK1 links upstream defense and growth signals to downstream factor in fungal resistance and growth homeostasis response regulators.

中文翻译：

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番茄受体样细胞质激酶TRK1对植物免疫和生长的调控

• 对真菌病原体的定量抗性 (QR) 的分子机制及其与生长途径的关系知之甚少。
• 我们鉴定了番茄 TRK1（TPK1b 相关激酶 1）并确定了它在番茄 QR 和植物生长中的功能。TRK1 是一种与番茄 LysM 受体激酶 (SlLYK1) 复合的受体样细胞质激酶。SlLYK1和TRK1是几丁质诱导的真菌抗性、活性氧积累和免疫反应基因表达所必需的。值得注意的是，TRK1 和 SlLYK1 在转录和转录后水平调节 SlMYC2，这是茉莉酸 (JA) 反应和真菌抗性的主要转录调节因子。
• 此外，TRK1 也是维持适当的分生组织生长所必需的，正如TRK1 RNAi 植物中的异位分生组织活性、增强的分枝和改变的花结构所揭示的那样。一致地，TRK1 与 SlCLV1 和 SlWUS 相互作用，并且TRK1 RNAi 植物在茎尖中显示出SlCLV3和SlWUS 的表达增加。有趣的是，TRK1 抑制分生组织中几丁质诱导的基因表达，但促进叶片中相同基因的表达。SlCLV1 和 TRK1 在防御中具有不同的功能，但在植物生长中具有相似的功能。
• 总体而言，通过与关键调节剂的分子和生化相互作用，TRK1 将上游防御和生长信号与真菌抗性和生长稳态反应调节剂的下游因子联系起来。