1 College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
2 Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education; and.
Mol Plant Microbe Interact. 2018 Mar;31(3):311-322. doi: 10.1094/MPMI-10-17-0240-R. Epub 2018 Jan 8.
Bacillus cereus AR156 (AR156) is a plant growth-promoting rhizobacterium capable of inducing systemic resistance to Pseudomonas syringae pv. tomato in Arabidopsis thaliana. Here, we show that, when applied to Arabidopsis leaves, AR156 acted similarly to flg22, a typical pathogen-associated molecular pattern (PAMP), in initiating PAMP-triggered immunity (PTI). AR156-elicited PTI responses included phosphorylation of MPK3 and MPK6, induction of the expression of defense-related genes PR1, FRK1, WRKY22, and WRKY29, production of reactive oxygen species, and callose deposition. Pretreatment with AR156 still significantly reduced P. syringae pv. tomato multiplication and disease severity in NahG transgenic plants and mutants sid2-2, jar1, etr1, ein2, npr1, and fls2. This suggests that AR156-induced PTI responses require neither salicylic acid, jasmonic acid, and ethylene signaling nor flagella receptor kinase FLS2, the receptor of flg22. On the other hand, AR156 and flg22 acted in concert to differentially regulate a number of AGO1-bound microRNAs that function to mediate PTI. A full-genome transcriptional profiling analysis indicated that AR156 and flg22 activated similar transcriptional programs, coregulating the expression of 117 genes; their concerted regulation of 16 genes was confirmed by real-time quantitative polymerase chain reaction analysis. These results suggest that AR156 activates basal defense responses to P. syringae pv. tomato in Arabidopsis, similarly to flg22.
蜡状芽孢杆菌 AR156（AR156）是一种能诱导拟南芥对丁香假单胞菌 pv.番茄产生系统性抗性的促生根际细菌。在这里，我们表明，当应用于拟南芥叶片时，AR156 类似于 flg22（一种典型的病原体相关分子模式（PAMP）），在启动 PAMP 触发的免疫（PTI）中发挥作用。AR156 诱导的 PTI 反应包括 MPK3 和 MPK6 的磷酸化、防御相关基因 PR1、FRK1、WRKY22 和 WRKY29 的表达诱导、活性氧的产生和胼胝质的沉积。AR156 预处理仍能显著降低 NahG 转基因植物和突变体 sid2-2、jar1、etr1、ein2、npr1 和 fls2 中丁香假单胞菌 pv.番茄的繁殖和严重程度。这表明 AR156 诱导的 PTI 反应既不需要水杨酸、茉莉酸和乙烯信号，也不需要鞭毛受体激酶 FLS2（flg22 的受体）。另一方面，AR156 和 flg22 协同作用，差异调节了许多 AGO1 结合的 microRNAs，这些 microRNAs介导 PTI。全基因组转录谱分析表明，AR156 和 flg22 激活了相似的转录程序，共同调控 117 个基因的表达；通过实时定量聚合酶链反应分析证实了它们对 16 个基因的协同调控。这些结果表明，AR156 类似于 flg22，激活了拟南芥对丁香假单胞菌 pv.番茄的基础防御反应。
