Plant Pathology and Plant Protection Division, Department of Crop Sciences, Faculty of Agriculture, Georg-August University Göttingen, Göttingen, Germany.
Agricultural Entomology Division, Department of Crop Sciences, Faculty of Agriculture, Georg-August University Göttingen, Göttingen, Germany.
Appl Environ Microbiol. 2024 Jun 18;90(6):e0058924. doi: 10.1128/aem.00589-24. Epub 2024 May 30.
Dormant microsclerotia play a vital role in the survival and spread of , as they can stay viable in the soil and maintain their infectivity for many years. In our previous work, we revealed that soil bacterial volatiles are a key inhibitory factor causing microsclerotia dormancy in the soil. In this study, we further demonstrate that root exudates collected from both host and non-host plants can effectively rescue microsclerotia from bacterial suppression and initiate germination. To identify the specific compounds in root exudates responsible for microsclerotia germination, we fractionated the collected root exudates into polar and non-polar compounds. Subsequently, we conducted comprehensive bioassays with each fraction on germination-suppressed microsclerotia. The result revealed a pivotal role of primary metabolites in root exudates, particularly glutamic acid, in triggering microsclerotia germination and overcoming bacterial inhibition. Moreover, our studies revealed a decrease in inhibitory bacterial volatile fatty acids when bacteria were cultured in the presence of root exudates or glutamic acid. This suggests a potential mechanism, by which root exudates set-off bacterial suppression on microsclerotia. Here, we reveal for the first time that plant root exudates, instead of directly inducing the germination of microsclerotia, enact a set-off effect by counteracting the suppressive impact of soil bacteria on the microsclerotia germination process. This nuanced interaction advances our understanding of the multifaceted dynamics governing microsclerotia dormancy and germination in the soil environment.
Our research provides first-time insights into the crucial interaction between plant root exudates and soil bacteria in regulating the germination of microsclerotia, a significant structure in the survival and proliferation of this soil-borne pathogen. We describe so far unknown mechanisms, which are key to understand how root infections on oilseed rape can occur. By pinpointing primary metabolites in root exudates as key factors in overcoming bacteria-induced dormancy and promote microsclerotia germination, our study highlights the potential for exploiting plant - as well as soil microbe-derived - compounds to control . This work underscores the importance of elucidating the nuanced interactions within the soil ecosystem to devise innovative strategies for managing root infective plant diseases, thereby contributing to the resilience and health of cropping systems.
休眠小菌核在 生存和传播中起着至关重要的作用，因为它们可以在土壤中保持活力，并保持多年的感染力。在我们之前的工作中，我们揭示了土壤细菌挥发物是导致土壤中小菌核休眠的关键抑制因素。在这项研究中，我们进一步证明，来自宿主和非宿主植物的根分泌物可以有效地从细菌抑制中拯救小菌核并启动萌发。为了确定根分泌物中负责小菌核萌发的特定化合物，我们将收集的根分泌物分为极性和非极性化合物。随后，我们用每个馏分对受抑制的小菌核进行了全面的生物测定。结果表明，根分泌物中的初级代谢物，特别是谷氨酸，在触发小菌核萌发和克服细菌抑制方面起着关键作用。此外，我们的研究还揭示了当细菌在根分泌物或谷氨酸存在的情况下培养时，抑制性细菌挥发性脂肪酸的减少。这表明了一种潜在的机制，即根分泌物通过抵消细菌对小菌核萌发过程的抑制作用来启动细菌抑制作用。在这里，我们首次揭示了植物根分泌物不是直接诱导小菌核萌发，而是通过抵消土壤细菌对小菌核萌发过程的抑制作用来产生抵消效应。这种细微的相互作用增进了我们对土壤环境中小菌核休眠和萌发的多方面动态的理解。
我们的研究首次提供了关于植物根分泌物和土壤细菌在调节 小菌核萌发方面的关键相互作用的见解，小菌核是这种土壤传播病原体生存和增殖的重要结构。我们描述了迄今为止未知的机制，这些机制是理解油菜根感染如何发生的关键。通过确定根分泌物中的初级代谢物作为克服细菌诱导休眠和促进小菌核萌发的关键因素，我们的研究强调了利用植物和土壤微生物衍生的化合物来控制 的潜力。这项工作强调了阐明土壤生态系统内细微相互作用的重要性，以设计管理根感染性植物病害的创新策略，从而为种植系统的弹性和健康做出贡献。
