Institute for Biology I, Unit of Plant Molecular Cell Biology, RWTH Aachen University, Worringerweg 1, 52056 Aachen, Germany.
Institute for Biology III, Department of Plant Physiology, RWTH Aachen University.
Mol Plant Microbe Interact. 2019 Sep;32(9):1243-1255. doi: 10.1094/MPMI-11-18-0304-R. Epub 2019 Jul 30.
Plants encounter beneficial and detrimental microorganisms both above- and belowground and the health status of the plant depends on the composition of this pan-microbiome. Beneficial microorganisms contribute to plant nutrition or systemically or locally protect plants against pathogens, thus facilitating adaptation to a variety of environments. Induced systemic resistance, caused by root-associated microbes, manifests as aboveground resistance against necrotrophic pathogens and is mediated by jasmonic acid/ethylene-dependent signaling. By contrast, systemic acquired resistance relies on salicylic acid (SA) signaling and confers resistance against secondary infection by (hemi)biotrophic pathogens. To investigate whether symbiotic rhizobia that are ubiquitously found in natural ecosystems are able to modulate resistance against biotrophs, we tested the impact of preestablished nodulation of and pea () plants against infection by the powdery mildew fungus . We found that root symbiosis interfered with fungal penetration of and reduced asexual spore formation on pea leaves independently of symbiotic nitrogen fixation. Improved resistance of nodulated plants correlated with elevated levels of free SA and SA-dependent marker gene expression upon powdery mildew infection. Our results suggest that nodulation primes the plants systemically for -triggered SA accumulation and defense gene expression, resulting in increased resistance.
植物在地上和地下都会遇到有益和有害的微生物，而植物的健康状况取决于这个泛微生物组的组成。有益的微生物有助于植物的营养，或者系统性或局部地保护植物免受病原体的侵害，从而促进植物适应各种环境。由根相关微生物引起的诱导系统抗性表现为地上对坏死型病原体的抗性，并由茉莉酸/乙烯依赖性信号转导介导。相比之下，系统获得抗性依赖于水杨酸 (SA) 信号转导，并赋予对 (半) 生物病原体二次感染的抗性。为了研究在自然生态系统中普遍存在的共生根瘤菌是否能够调节对生物病原体的抗性，我们测试了预先建立的 和豌豆 () 植物的根瘤形成对白粉菌真菌感染的影响。我们发现，根共生关系干扰了 的真菌穿透，并独立于共生固氮减少了豌豆叶片上无性孢子的形成。接种植物的抗性提高与白粉病感染后游离 SA 水平升高和 SA 依赖性标记基因表达相关。我们的研究结果表明，根瘤菌使植物系统性地对 触发的 SA 积累和防御基因表达进行了“预编程”，从而提高了抗性。
