Kelly Simon, Mun Terry, Stougaard Jens, Ben Cécile, Andersen Stig U
Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
ECOLAB, Université de Toulouse, CNRS, INP, UPS, Toulouse, France.
Front Plant Sci. 2018 Aug 20;9:1218. doi: 10.3389/fpls.2018.01218. eCollection 2018.
is a well-studied nodulating legume and a model organism for the investigation of plant-microbe interactions. The majority of legume transcriptome studies have focused on interactions with compatible symbionts, whereas responses to non-adapted rhizobia and pathogenic bacteria have not been well-characterized. In this study, we first characterized the transcriptomic response of to its compatible symbiont, R7A, through RNA-seq analysis of various plant tissues. Early symbiotic signaling was largely Nod factor-dependent and enhanced within root hairs, and we observed large-scale transcriptional reprogramming in nodule primordia and mature nitrogen-fixing nodules. We then characterized root transcriptional responses to a spectrum of interacting bacteria ranging from semi-compatible symbionts to pathogens. R7A and the semi-compatible strain HH103 showed remarkably similar responses, allowing us to identify a small number of genes potentially involved in differentiating between fully and semi-compatible symbionts. The incompatible symbiont USDA61 induced a more attenuated response, but the weakest response was observed for the foliar pathogen pv. DC3000, where the affected genes also responded to other tested bacteria, pointing to a small set of common bacterial response genes. In contrast, the root pathogen JS763 induced a pronounced and distinct transcriptomic pathogen response, which we compared to the results of the other treatments. This comparative analysis did not support the concept that an early defense-like response is generally evoked by compatible rhizobia during establishment of symbiosis.
是一种经过充分研究的结瘤豆科植物，也是用于研究植物-微生物相互作用的模式生物。大多数豆科植物转录组研究都集中在与相容共生体的相互作用上，而对非适应性根瘤菌和病原菌的反应尚未得到很好的表征。在本研究中，我们首先通过对各种植物组织的RNA测序分析，表征了其对相容共生体R7A的转录组反应。早期共生信号在很大程度上依赖于结瘤因子，并在根毛中增强，我们在根瘤原基和成熟固氮根瘤中观察到大规模的转录重编程。然后，我们表征了根系对一系列相互作用细菌的转录反应，这些细菌范围从半相容共生体到病原菌。R7A和半相容菌株HH103表现出非常相似的反应，这使我们能够鉴定出少数可能参与区分完全相容和半相容共生体的基因。不相容共生体USDA61诱导的反应较为减弱，但对叶部病原菌丁香假单胞菌番茄致病变种DC3000的反应最弱，其中受影响的基因也对其他测试细菌有反应，这表明存在一小部分共同的细菌反应基因。相比之下，根部病原菌JS763诱导了明显且独特的转录组病原菌反应，我们将其与其他处理结果进行了比较。这种比较分析不支持在共生建立过程中相容根瘤菌通常会引发早期类似防御反应的概念。
