小麦蚕豆间作调控小麦白粉病抗性的氮代谢分子机制

Powdery mildew caused by Blumeria gramins f.sp.tritici is one of the most devastating foliar diseases for wheat in the world, which severely influences yield and quality of wheat. Nitrogen application and nitrogen metabolism influence occurrence of wheat powdery mildew. Wheat and faba bean intercropping is an effective practice to enhance the yield of wheat and control the occurrence of wheat powdery mildew. Former researches illustrated that wheat and faba bean intercropping could regulate nitrogen metabolism of wheat, and the occurrence of wheat powdery mildew closely related to changing nitrogen metabolism in intercropping system. However, the characteristic of nitrogen metabolism in intercropping is still unclear. How intercropping regulates nitrogen metabolisms and induces the resistant response of wheat is unknown. The present study focus on intercropping regulates nitrogen metabolisms-induces antioxidant response -decreases powdery mildew in wheat and faba bean intercropping system through fields and pots experiments in green house with inoculation and non- inoculation of Blumeria gramins f.sp.tritici under different nitrogen levels. Some key methods and techniques for monitoring dynamic processes and related parameters in the nitrogen metabolites are adopted including LC-MS and RT-qPCR. The main objectives of the present study are to systematically investigate the characteristics of nitrogen metabolisms in intercropping wheat including nitrogen uptake and utilization, nitrogen metabolites, activity of key enzymes related to nitrogen metabolism (GS/GOGAT), clarify encoded gene related to nitrogen metabolism of intercropping wheat and transcriptional gene expression analysis, and reveal the nitrogen metabolism mechanism in intercropping regulates wheat nitrogen nutrition, induces wheat resistance and decreases diseases occurrence .The research is of scientific and practical importance not only for comprehensive understands biodiversity maintains stability of agro-ecosystem, but also for realizes sustainable production of wheat and reduces fertilizers and fungicides.

白粉病是影响小麦产量和品质的世界性病害，氮肥施用及氮代谢与小麦白粉病发生密切相关。小麦蚕豆间作能提高小麦产量、控制白粉病的发生。前期研究表明，间作改变了小麦氮代谢，且氮代谢改变影响白粉病的发生。但，间作系统氮代谢特征尚不清楚，间作调控氮代谢进而介导小麦抗性的机制尚不明晰。本研究通过大田试验和盆栽试验，以小麦蚕豆间作体系为研究对象，在接种/不接种白粉病菌下，以间作调控小麦氮代谢、介导小麦抗氧化反应、降低小麦白粉病发生的机制为主线，采用LC-MS检测结合RT-qPCR分子手段等方法，系统研究不同氮水平下，间作小麦的氮代谢(氮吸收利用、氮代谢产物、氮代谢关键酶(GS/GOGAT))特征；解析间作小麦氮代谢关键基因的克隆及表达；揭示间作调控小麦氮营养-介导小麦抗性-降低白粉病的氮代谢分子机制。研究对全面理解生物多样性维持农田生态系统稳定性、实现小麦可持续生产、节肥减药具有重要的理论和现实意义。

小麦蚕豆间作能促进小麦氮素吸收、同时降低小麦白粉病的发生，但其具体作用机制不清楚。研究通过田间试验和培养试验，系统分析了不同氮水平下小麦蚕豆间作对作物氮素吸收累积分配的影响，探讨了单间作小麦功能叶片氮代谢关键酶活性、基因表达量及叶片初生代谢物的差异。分析了病原菌侵染时单间作小麦抗性酶和氮代谢酶活性差异，利用广泛非靶向代谢组分析技术，系统分析了病原菌侵染时、单间作小麦差异代谢物。研究发现间作提高小麦氮吸收速率和氮素累积量 15.1%～48.4%和 9.2%～28.9%。但是，除小麦拔节期，间作并未提高小麦叶片和茎秆中氮含量。间作显著上调了旗叶中谷氨酸合酶和谷氨酰胺合成酶（GS1、GS2、Fd-GOGAT、NADH-GOGAT）的酶活性和基因表达量，促进了氮素由叶片和茎秆向籽粒转移。与单作相比，在拔节期，低氮供应条件下，间作显著上调了叶片中酚酸类化合物；高氮供应条件下间作上调了有机酸类、改变了氨基酸生物合成。因此，间作上调GS和GOGAT活性促进叶片和茎秆氮转移、上调叶片酚酸类和有机酸类化合物、调控氨基酸的生物合成，是间作提高小麦抗性的生理基础。当小麦白粉病病原菌侵染时，与单作相比，间作小麦GS和GOGAT酶活变化较小。白粉病发病后，间作上调了小麦叶片中氨基酸及其衍生物类，其中主要是调控了与作物抗性相关的氨基酸类差异代谢物：如γ-氨基丁酸（GABA）等病原菌侵染所需的能量来源；苯丙氨酸、色氨酸、脯氨酸、N-乙酰鸟氨酸等植物抗性相关基础物质。研究证实，间作调控氨基酸生物合成及ABC转运蛋白，调控叶片氨基酸类差异代谢物是间作降低白粉病的氮代谢生理机制。研究系统解释了小麦蚕豆间作调控氮素吸收利用提高小麦抗白粉病的氮代谢生理机制。通过项目的实施，累计发表论文9篇（SCI 2篇，中文核心6篇），待发表论文3篇；培养硕士生5人，本科生10人。新增云南省青年拔尖人才2人，新增教授1人。