• Below‐ground microbes can induce systemic resistance against foliar pests and pathogens on diverse plant hosts. The prevalence of induced systemic resistance (ISR) among plant‐microbe‐pest systems raises the question of host specificity in microbial induction of ISR.
• To test whether ISR is limited by plant host range_, we tested the ISR‐inducing ectomycorrhizal fungus Laccaria bicolor on the nonmycorrhizal plant Arabidopsis thaliana. We used the cabbage looper Trichoplusia ni and bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pto) as readouts for ISR on Arabidopsis.
• We found that root inoculation with L. bicolor triggered ISR against T. ni and induced systemic susceptibility (ISS) against the bacterial pathogen Pto. We found that L. bicolor‐triggered ISR against T. ni was dependent on jasmonic acid signaling and salicylic acid biosynthesis and signaling. Heat‐killed L. bicolor and chitin were sufficient to trigger ISR against T. ni and ISS against Pto. The chitin receptor CERK1 was necessary for L. bicolor‐mediated effects on systemic immunity.
• Collectively our findings suggest that some ISR responses might not require intimate symbiotic association, but rather might be the result of root perception of conserved microbial signals.

中文翻译：

---

外生菌根真菌以依赖CERK1的方式诱导对非菌根植物上的昆虫的系统抗性。

• 地下微生物可诱导对多种植物宿主上的叶类害虫和病原体的系统抗性。在植物-微生物-害虫系统中普遍存在诱导系统抗性（ISR），这提出了在ISR微生物诱导中宿主特异性的问题。
• 为了测试ISR是否受植物寄主范围的限制_，我们在无菌根植物拟南芥上测试了诱导ISR的外生菌根真菌双色紫胶菌。我们使用了卷心菜弯管虫Trichoplusia ni和细菌性病原体丁香假单胞菌pv。番茄DC3000（Pto）作为拟南芥ISR的读数。
• 我们发现用双色乳杆菌根部接种可触发针对T. ni的ISR，并诱导针对细菌病原体Pto的全身敏感性（ISS）。我们发现，L. bicolor-触发ISR对T.妮依赖于茉莉酸信号和水杨酸生物合成和信令。加热杀死的双色乳酸杆菌和几丁质足以引发针对T. ni的ISR和针对Pto的ISS 。甲壳质受体CERK1是双色乳杆菌介导的对全身免疫的作用所必需的。
• 总的来说，我们的发现表明某些ISR反应可能不需要密切的共生联系，而可能是根源对保守微生物信号的感知。