Mavrodi Olga V, McWilliams Janiece R, Peter Jacob O, Berim Anna, Hassan Karl A, Elbourne Liam D H, LeTourneau Melissa K, Gang David R, Paulsen Ian T, Weller David M, Thomashow Linda S, Flynt Alex S, Mavrodi Dmitri V
School of Biological, Environmental, and Earth Sciences, The University of Southern Mississippi, Hattiesburg, MS, United States.
Institute of Biological Chemistry, Washington State University, Pullman, WA, United States.
Front Microbiol. 2021 Apr 14;12:651282. doi: 10.3389/fmicb.2021.651282. eCollection 2021.
Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the group and , a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains' pangenome, reflecting the importance of the variable gene content in the adaptation of to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts.
植物与微生物共生，这些微生物能积极影响植物的发育、活力以及应对病原体和非生物胁迫时的适应性。植物微生物组的大部分集中在地下的植物根 - 土界面。植物根系分泌富含碳的根际分泌物，其中包含初级和次级低分子量代谢物、裂解物和黏液。这些分泌物为土壤微生物提供养分，并调节它们与宿主植物的亲和力，但这一过程的分子细节在很大程度上尚未明确。我们通过聚焦于该组八个特征明确的有益菌株与作为禾本科经济上重要的粮食、饲料、草料和生物质作物模型之间的分子对话，填补了这一空白。我们收集并分析了该作物的根系分泌物，证明其中存在多种碳水化合物、氨基酸、有机酸和酚类化合物。随后通过Biolog表型微阵列对细菌进行筛选，结果表明这些代谢物中的许多为该菌株提供了碳源和能量。用根系分泌物改良细菌培养物后的RNA测序分析显示，编码众多分解代谢和合成代谢酶、转运蛋白、转录调节因子、应激反应和保守假设蛋白的基因表达发生了变化。几乎一半的差异表达基因映射到该菌株泛基因组的可变部分，这反映了可变基因内容在该菌株适应根际生活方式中的重要性。我们的研究结果共同揭示了这些有益根际细菌与其植物宿主之间建立互利相互作用背后细胞途径和生理反应的多样性。
