Plant J|福建农林大学唐定中和刘娜共同通讯在TIR‐NBS（TN）植物免疫蛋白方面研究取得新进展

核苷酸结合-富含亮氨酸重复序列（NLR）蛋白通过识别病原效应物在植物天然免疫中发挥重要作用。TIR‐NBS（TN）蛋白属于非典型NLRs的一个亚型，但其在植物免疫中的作用尚不清楚。拟南芥（Arabidopsis thaliana，拟南芥）对丁香假单胞菌5（PSEUDOMONAS SYRINGAE 5，RPS5）的典型CC-NBS-LRR（CNL）蛋白抗性在识别了丁香假单胞菌III型效应子AvrPphB后被激活。

为了探讨截短的TN蛋白是否在CNL介导的免疫信号中起作用，我们检测了拟南芥TN蛋白与RPS5之间的相互作用，发现TN13和TN21与RPS5相互作用。然而，只有TN13而不是TN21参与了对丁香假单胞菌pv的抗性。

番茄（Pto）菌株DC3000携带avrPphB，RPS5识别的同源效应子。此外，TN13对Pto DC3000 avrPphB抗性的调节似乎是特异性的，因为TN13功能的丧失不会损害对Pto DC3000 hrcC或Pto DC3000 avrRpt2的抗性。此外，我们证明了RPS5的CC和NBS结构域在TN13和RPS5之间的相互作用中起着重要作用。

综上所述，我们的结果揭示了TN13和RPS5之间的直接功能联系，表明TN13可能作为调节RPS5激活的免疫信号的一个伙伴，这构成了TN介导的植物免疫调节的一个以前未知的机制。

Nucleotide binding‐leucine rich repeat (NLR) proteins play important roles in plant innate immunity by recognizing pathogen effectors. The TIR‐NBS (TN) proteins belong to a subtype of the atypical NLRs, but their function in plant immunity is poorly understood. The well‐characterized Arabidopsis thaliana (Arabidopsis) typical CC‐NBS‐LRR (CNL) protein RESISTANCE TO PSEUDOMONAS SYRINGAE 5 (RPS5) is activated after recognizing the Pseudomonas syringae type III effector AvrPphB. To explore whether the truncated TN proteins function in CNL‐mediated immune signaling, we examined the interactions between the Arabidopsis TN proteins and RPS5, and found that TN13 and TN21 interacted with RPS5. However, only TN13, but not TN21, was involved in the resistance to Pseudomonas syringae pv. tomato (Pto) strain DC3000 carrying avrPphB, the cognate effector recognized by RPS5. Moreover, the regulation of Pto DC3000 avrPphB resistance by TN13 appeared to be specific, as loss of function of TN13 did not compromise resistance to Pto DC3000 hrcC– or Pto DC3000 avrRpt2. In addition, we demonstrated that the CC and NBS domains of RPS5 play essential roles in the interaction between TN13 and RPS5. Taken together, our results uncover a direct functional link between TN13 and RPS5, suggesting that TN13 may act as a partner in modulating RPS5‐activated immune signaling, which constitutes a previously unknown mechanism for TN‐mediated regulation of plant immunity.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.15345?af=R

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