Department of Molecular Physiology: Applied Metabolome Analysis, Max-Planck-Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany.
Sci Rep. 2018 Jan 9;8(1):216. doi: 10.1038/s41598-017-18397-5.
Plants evolved mechanisms to counteract bacterial infection by preparing yet uninfected systemic tissues for an enhanced defense response, so-called systemic acquired resistance or priming responses. Primed leaves express a wide range of genes that enhance the defense response once an infection takes place. While hormone-driven defense signalling and defensive metabolites have been well studied, less focus has been set on the reorganization of primary metabolism in systemic leaves. Since primary metabolism plays an essential role during defense to provide energy and chemical building blocks, we investigated changes in primary metabolism at RNA and metabolite levels in systemic leaves of Arabidopsis thaliana plants that were locally infected with Pseudomonas syringae. Known defense genes were still activated 3-4 days after infection. Also primary metabolism was significantly altered. Nitrogen (N)-metabolism and content of amino acids and other N-containing metabolites were significantly reduced, whereas the organic acids fumarate and malate were strongly increased. We suggest that reduction of N-metabolites in systemic leaves primes defense against bacterial infection by reducing the nutritional value of systemic tissue. Increased organic acids serve as quickly available metabolic resources of energy and carbon-building blocks for the production of defense metabolites during subsequent secondary infections.
植物进化出了多种机制来抵御细菌感染，为尚未感染的系统组织做好准备，以增强防御反应，即系统获得性抗性或免疫原性反应。被免疫的叶片表达一系列基因，一旦发生感染，就会增强防御反应。虽然激素驱动的防御信号和防御性代谢物已经得到了充分研究，但对系统叶片中初级代谢物的重组关注较少。由于初级代谢物在防御过程中起着至关重要的作用，为防御提供能量和化学构建块，我们研究了拟南芥局部感染丁香假单胞菌后系统叶片的初级代谢物在 RNA 和代谢物水平上的变化。在感染后 3-4 天，已知的防御基因仍被激活。同时，初级代谢物也发生了显著改变。氮代谢和氨基酸和其他含氮代谢物的含量显著降低，而富马酸和马来酸等有机酸则显著增加。我们认为，系统叶片中氮代谢物的减少通过降低系统组织的营养价值来为防御细菌感染做好准备。增加的有机酸可作为能量和碳构建块的快速可用代谢资源，用于随后的次生感染中防御性代谢物的产生。
