Microbe-associated molecular patterns (MAMPs) are conserved molecules able to trigger plant resistance. The aim of this work was to evaluate the capacity of Azospirillum brasilense REC3 polar flagellin AzFlap as a MAMP, eliciting biochemical, histological, and molecular defense responses that can provide strawberry plants protection against the pathogenic fungus Macrophomina phaseolina. Strawberry plants were treated with AzFlap on leaves or with the isolate REC3 on leaves or roots. Salicylic acid content, biofilm formation, callose and lignin depositions, stomatal closure, ROS, and the expression of defense-related genes such as FaPR1, FaCAT, FaRBOH-D, FaRBOH-F, FaCHI23, FaCHI2-2, and FaGSL5 were evaluated. Phytopathogenic assays in plants treated with AzFlap or REC3 and infected with M. phaseolina were also performed. Results showed that plants leaf treated with AzFlap or root treated with REC3 caused the accumulation of ROS, salicylic acid, callose, lignin, the increase of biofilm formation on leaves, and stomatal closure. The evaluation of the expression of genes associated to defense response indicated the activation of the innate immunity of strawberry plants. The level of gene expression was strongly time and treatment dependent, suggesting a complex regulation of defense signaling. Root inoculations with REC3 or foliar treatment with AzFlap were able to reduce plant mortality, showing the effectiveness of both treatments to control M. phaseolina. These results indicate that flagellin AzFlap from A. brasilense REC3 behaves as a MAMP that activates a defense response against M. phaseolina in strawberry plants.

微生物相关分子模式 (MAMP) 是能够引发植物抗性的保守分子。这项工作的目的是能力评估巴西固氮螺菌REC3极性鞭毛蛋白AzFlap作为MAMP，引发生化，组织和分子的防御反应，可以提供对致病性真菌草莓植株保护Macrophomina phaseolina。草莓植物在叶子上用 AzFlap 或在叶子或根上用分离株 REC3 处理。水杨酸含量、生物膜形成、胼胝质和木质素沉积、气孔闭合、ROS，以及防御相关基因的表达，如FaPR1、FaCAT、FaRBOH-D、FaRBOH-F、评估了 FaCHI23、FaCHI2-2和FaGSL5。与AzFlap或REC3治疗，感染植物抗病原测定M. phaseolina也进行了。结果表明，用 AzFlap 处理的植物叶片或用 REC3 处理的根引起 ROS、水杨酸、胼胝质、木质素的积累，叶片上生物膜形成的增加和气孔关闭。对防御反应相关基因表达的评估表明草莓植物先天免疫的激活。基因表达水平强烈依赖于时间和治疗，表明防御信号的复杂调节。用 REC3 进行根部接种或用 AzFlap 进行叶面处理能够降低植物死亡率，这表明两种处理对控制小菜豆的有效性。这些结果表明来自A. brasilense 的鞭毛蛋白 AzFlapREC3 充当 MAMP，激活草莓植物中针对M. phaseolina的防御反应。