PDF(Pubmed)
Abstract：
Xylanases derived from fungi, including phytopathogenic and nonpathogenic fungi, are commonly known to trigger plant immune responses. However, there is limited research on the ability of bacterial-derived xylanases to trigger plant immunity. Here, a novel xylanase named CcXyn was identified from the myxobacterium Cystobacter sp. 0969, which displays broad-spectrum activity against both phytopathogenic fungi and bacteria. CcXyn belongs to the glycoside hydrolases (GH) 11 family and shares a sequence identity of approximately 32.0%-45.0% with fungal xylanases known to trigger plant immune responses. Treatment of Nicotiana benthamiana with purified CcXyn resulted in the induction of hypersensitive response (HR) and defence responses, such as the production of reactive oxygen species (ROS) and upregulation of defence gene expression, ultimately enhancing the resistance of N. benthamiana to Phytophthora nicotianae. These findings indicated that CcXyn functions as a microbe-associated molecular pattern (MAMP) elicitor for plant immune responses, independent of its enzymatic activity. Similar to fungal xylanases, CcXyn was recognized by the NbRXEGL1 receptor on the cell membrane of N. benthamiana. Downstream signalling was shown to be independent of the BAK1 and SOBIR1 co-receptors, indicating the involvement of other co-receptors in signal transduction following CcXyn recognition in N. benthamiana. Moreover, xylanases from other myxobacteria also demonstrated the capacity to trigger plant immune responses in N. benthamiana, indicating that xylanases in myxobacteria are ubiquitous in triggering plant immune functions. This study expands the understanding of xylanases with plant immune response-inducing properties and provides a theoretical basis for potential applications of myxobacteria in biocontrol strategies against phytopathogens.
摘要：
来自真菌的木聚糖酶，包括植物病原性和非病原性真菌，通常已知会引发植物免疫反应。然而,关于细菌来源的木聚糖酶触发植物免疫的能力的研究有限。这里,一种名为CcXyn的新型木聚糖酶是从粘杆菌属杆菌属杆菌属中鉴定出来的。0969，对植物病原性真菌和细菌均具有广谱活性。CcXyn属于糖苷水解酶（GH）11家族，与已知触发植物免疫反应的真菌木聚糖酶具有约32.0％-45.0％的序列同一性。用纯化的CcXyn治疗本氏烟草导致诱导超敏反应（HR）和防御反应，例如活性氧（ROS）的产生和防御基因表达的上调，最终增强了N.benthamiana对烟草疫霉的抗性。这些发现表明，CcXyn作为植物免疫反应的微生物相关分子模式（MAMP）诱导子，独立于其酶活性。类似于真菌木聚糖酶，CcXyn被N.benthamiana细胞膜上的NbRXEGL1受体识别。下游信号显示独立于BAK1和SOBIR1共受体，表明在N.benthamiana中CcXyn识别后，其他共受体参与信号转导。此外，来自其他粘细菌的木聚糖酶也证明了在N.benthamiana中触发植物免疫反应的能力，表明粘细菌中的木聚糖酶在触发植物免疫功能方面普遍存在。这项研究扩展了对具有植物免疫应答诱导特性的木聚糖酶的理解，并为粘细菌在针对植物病原体的生物控制策略中的潜在应用提供了理论基础。
