Adss Shimaa, Liu Benye, Beerhues Ludger, Hahn Volker, Heuer Holger, Elhady Ahmed
Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn-Institute, Federal Research Centre for Cultivated Plants, Braunschweig, Germany.
Institute of Pharmaceutical Biology, Technische Universität Braunschweig, Braunschweig, Germany.
Front Plant Sci. 2021 May 12;12:651943. doi: 10.3389/fpls.2021.651943. eCollection 2021.
Root lesion nematodes, , are major pests of legumes with little options for their control. We aimed to prime soybean cv. Primus seedlings to improve basic defense against these nematodes by root application of -3-oxo-tetradecanoyl--homoserine lactone (oxo-C14-HSL). The invasion of soybean roots by was significantly reduced in plants that were pre-treated with the oxo-C14-HSL producing rhizobacterium strain ExpR+, compared to non-inoculated plants or plants inoculated with the nearly isogenic strain AttM with plasmid-mediated oxo-C14-HSL degradation. The nematodes were more clustered in the root tissues of plants treated with the AttM strain or the control compared to roots treated with the ExpR+ strain. In split-root systems primed on one side with strain ExpR+, root invasion was reduced on the opposite side compared to non-primed plants indicating a systemic plant response to oxo-C14-HSL. No additional local effect was detected, when inoculating nematodes on the ExpR+ primed side. Removal of oxo-C14-HSL after root exposure resulted in reduced root invasion compared to non-primed plants when the nematodes were added 3, 7, or 15 days later. Thus, probably the plant memorized the priming stimulus. Similarly, the plants were primed by compounds released from the surface of the nematodes. HPLC analysis of the root extracts of oxo-C14-HSL treated and untreated plants revealed that priming resulted in enhanced phytoalexin synthesis upon challenge. Without root invading nematodes, the phytoalexin concentrations of primed and non-primed plants did not significantly differ, indicating that priming did not lead to a persistently increased stress level of the plants. Upon nematode invasion, the phytoalexins coumestrol, genistein, and glyceollin increased in concentration in the roots compared to control plants without nematodes. Glyceollin synthesis was significantly more triggered by nematodes in primed plants compared to non-primed plants. The results indicated that the priming of soybean plants led to a more rapid and strong defense induction upon root invasion of nematodes.
根结线虫是豆类作物的主要害虫，防治方法有限。我们旨在通过根部施用N-3-氧代十四烷酰-L-高丝氨酸内酯（oxo-C14-HSL）来预处理大豆品种Primus幼苗，以增强对这些线虫的基础防御能力。与未接种的植株或接种了具有质粒介导的oxo-C14-HSL降解功能的近等基因菌株AttM的植株相比，用产生oxo-C14-HSL的根际细菌ExpR+菌株预处理的植株中，大豆根被线虫的侵染显著减少。与用ExpR+菌株处理的根相比，线虫在用AttM菌株或对照处理的植株的根组织中聚集得更多。在一侧用ExpR+菌株预处理的分根系统中，与未预处理的植株相比，另一侧的根侵染减少，这表明植物对oxo-C14-HSL有系统反应。当在线虫侵染ExpR+预处理的一侧接种线虫时，未检测到额外的局部效应。与未预处理的植株相比，在根部暴露后去除oxo-C14-HSL，当线虫在3、7或15天后添加时，根侵染减少。因此，植物可能记住了预处理刺激。同样，植物也被线虫表面释放的化合物预处理。对经oxo-C14-HSL处理和未处理的植株的根提取物进行高效液相色谱分析表明，预处理导致在受到线虫挑战时植保素合成增强。在没有根际侵入线虫的情况下，预处理和未预处理植株的植保素浓度没有显著差异，这表明预处理并没有导致植物应激水平持续升高。在线虫侵染后，与没有线虫的对照植株相比，根中植保素香豆雌酚、染料木黄酮和大豆抗毒素的浓度增加。与未预处理的植株相比，线虫在预处理植株中对大豆抗毒素合成的触发作用明显更强。结果表明，大豆植株的预处理导致在根际线虫侵染时更快、更强地诱导防御反应。
