Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China.
Key Laboratory of Agricultural Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.
Plant Cell Environ. 2021 Sep;44(9):3094-3102. doi: 10.1111/pce.14068. Epub 2021 May 3.
Efficient root colonization of plant growth-promoting rhizobacteria is critical for their plant-beneficial functions. However, the strategy to overcome plant immunity during root colonization is not well understood. In particular, how Bacillus strains cope with plant-derived reactive oxygen species (ROS), which function as the first barrier of plant defence, is not clear. In the present study, we found that the homolog of flg22 in Bacillus velezensis SQR9 (flg22 ) has 78.95% identity to the typical flg22 (flg22 ) and induces a significant oxidative burst in cucumber and Arabidopsis. In contrast to pathogenic or beneficial Pseudomonas, live B. velezensis SQR9 also induced an oxidative burst in cucumber. We further found that B. velezensis SQR9 tolerated higher H O levels than Pst DC3000, the pathogen that harbours the typical flg22, and that it possesses the ability to suppress the flg22-induced oxidative burst, indicating that B. velezensis SQR9 may exploit a more efficient ROS tolerance system than DC3000. Further experimentation with mutagenesis of bacteria and Arabidopsis showed that the two-component regulatory system, ResDE, in B. velezensis SQR9 is involved in tolerance to plant-derived oxidative stress, thus contributing to root colonization. This study supports a further investigation of the interaction between beneficial rhizobacteria and plant immunity.
植物促生根际细菌的高效定殖对于其发挥植物有益功能至关重要。然而，它们在根际定殖过程中克服植物免疫的策略尚未被充分理解。特别是，芽孢杆菌菌株如何应对植物来源的活性氧（ROS），ROS 作为植物防御的第一道屏障，目前尚不清楚。在本研究中，我们发现解淀粉芽孢杆菌 SQR9 中的 flg22 同源物（flg22 ）与典型的 flg22 （flg22 ）具有 78.95%的同一性，并在黄瓜和拟南芥中诱导了显著的氧化爆发。与致病性或有益的假单胞菌不同，活的解淀粉芽孢杆菌 SQR9 也能在黄瓜中诱导氧化爆发。我们进一步发现，解淀粉芽孢杆菌 SQR9 能够耐受比含有典型 flg22 的病原菌 Pst DC3000 更高的 H2O2 水平，并且它具有抑制 flg22 诱导的氧化爆发的能力，这表明解淀粉芽孢杆菌 SQR9 可能利用比 DC3000 更有效的 ROS 耐受系统。进一步对细菌和拟南芥进行诱变实验表明，解淀粉芽孢杆菌 SQR9 中的双组分调控系统 ResDE 参与了对植物来源的氧化应激的耐受，从而有助于定殖。这项研究支持了对有益根际细菌与植物免疫之间相互作用的进一步研究。
