盐胁迫下水稻根际微域氮素转化机理及关键功能微生物驱动机制

The soil productivity and the rice productivity in saline region are limited by the nitrogen (N) availability in soil. The rice rhizosphere is an interactive zone where microbes living, N migrating and transforming, and N absorbing by rice plants. The interactions of these three factors in rhizosphere can directly affect the N supplying capacity in soil and the N uptake in rice plants. However, the key processes and the driving mechanism for N transformations in the rice rhizosphere regulated by functional microbes under salt stress are still unknown. The response ways of rice plants to functional microbes under salt stress are still unclear. In this project, soil in rice rhizosphere under salt stress will be treated as study object, salt-tolerance rice and salt-sensitive rice will be used as rice varieties, and functional microbes related with N transformation processes will be used as the regulating way. The succession law for microbe community composition in rice rhizosphere under salt stress will be analyzed, the driving mechanism for the key functional microbes to N transformations in rice rhizosphere under salt stress will be illuminated, the physiological response ways and the molecular response mechanisms for rice plants to functional microbes under salt stress will be revealed, and the interactive mechanism among N transformations in rhizosphere, rice growth and development, and the key functional microbes will be determined. The study will improve N supplying capacity in soil under salt stress, and accelerate the N movement from rhizopshere to rice roots. The study can provide theoretical basis and technical support for the high efficient utilization of soil resource and improvement of rice grain yield potential in saline region.

盐渍区稻田土壤和水稻生产力受到氮素有效性的限制。根际微域是微生物活动、土壤氮素迁移转化、水稻氮素吸收的直接区系，这三者的交互作用直接影响到土壤供氮潜能及水稻对氮素的有效吸收。目前盐胁迫下功能微生物介入水稻根际微域调控氮素转化的关键过程及驱动机制尚不清楚，水稻对盐胁迫下功能微生物的响应途径尚不明确。本项目以盐胁迫水稻根际微域土壤为研究对象，以耐盐水稻、盐敏感水稻为供试材料，以氮素转化关键功能微生物为介入手段，解析盐胁迫下水稻根际微域微生物群落结构演替规律，阐明盐胁迫下关键功能微生物介入对根际微域氮素转化的驱动机制，揭示盐胁迫下水稻植株对关键功能微生物介入的生理响应途径及分子应答机制，明确根际微域氮素转化-水稻生长发育-关键功能微生物的交互作用机制，提高土壤氮素供应潜力，加强氮素由根际微域向水稻根系的迁移。以期为盐渍区土壤资源高效利用及提升盐渍土水稻产量潜力提供理论基础和技术支持。

盐渍区稻田土壤和水稻生产力受到氮素有效性的限制。根际微域是微生物活动、土壤氮素迁移转化、水稻氮素吸收的直接区系，这三者的交互作用直接影响到土壤供氮潜能及水稻对氮素的有效吸收。外源功能微生物可在一定程度上实现逆境胁迫下水稻根际互作的正向驱动，改变根际微域的物质循环与能量流动。本项目通过在水稻根际微域介入耐盐性能较强的巴西固氮螺菌（A. brasilence）与荧光假单胞菌（P. fluorescens），盐胁迫土壤氨化作用进程、硝化作用进程、生物固氮进程得到显著优化，土壤氮素供应潜力与有效性显著提升；根际微生物群落多样性提升，群落结构更趋于富营养型稻田土壤；同时A. brasilence与P. fluorescens的互作可提升水稻根系耐盐适应性，提高水稻植株耐盐基因表达与渗透性能，水稻生长发育特征与对照相比显著提高。大田评价结果表明，较低氮水平下（90-180 kg N hm-2）水稻根际微域介入A. brasilence与P. fluorescens可显著增加盐渍区水稻产量与氮肥利用效率。本项目研究成果对提升盐渍区土壤地力水平、增强水稻吸氮能力、完善盐渍区水稻种植栽培技术体系、开发利用盐渍区土地资源具有重要价值。