根际是植物与微生物相互作用的中心场所，一方面植物通过根系分泌物为根际微生物生长提供基质，另一方面根际微生物可以产生有利于植物的代谢产物，在植物健康和抵御环境胁迫方面发挥重要作用。吲哚乙酸（IAA）是最重要也是最常见的天然生长素，其产生菌普遍存在于植物根际。然而在最主要的粮食作物水稻根际，根系分泌物与IAA产生菌相互作用的分子机理尚不清楚。本项目拟采用稳定性同位素核酸探针技术耦合宏基因组测序、实时荧光定量PCR技术和抑制剂法分步研究水稻根系分泌物对IAA产生菌群落以及IAA合成功能基因丰度和转录活性的影响、IAA产生菌对根系及分泌物的反馈作用，同时结合水培分根实验，探索IAA产生菌菌株接种对根系分泌物的影响以及这种影响对菌株并最终反馈到植株（菌→根系分泌物→菌→植株）的作用，最终阐明水稻根系分泌物与IAA产生菌互作的分子机理，为加深了解水稻根际生物学过程，发展可持续、无公害农业提供科学依据。

Rhizosphere is the central place where plant-microbe interactions occur. Plant supplies substrates to microorganisms in the rhizosphere through root exudates; on the other hand, metabolites of rhizospheric microorganisms may be beneficial for the plant, and play an important role for plant health and defense against environmental stress. Indole-3-acetic acid (IAA) is the most common natural auxin. Production of IAA is widespread among bacteria that inhabit the rhizosphere of plants. However, the molecular mechanisms of interaction between root exudates and IAA-producing bacteria in the rice rhizosphere are unclear, even though rice is the main food crop for many countries. In this research program, we will study the impact of root exudates of rice on communities of IAA-producing bacteria and abundance and transcription of IAA-synthesizing functional genes, and feedback of IAA-producing bacteria on root, using DNA based stable isotope probing, coupled metagenomic sequencing, real-time fluorescence quantitative PCR technology and the use of inhibitors. The impact of IAA-producing bacteria inoculation on root exudates, the feedback on IAA-producing bacteria, and the final effect on the plant is explored by split-root experiment (bacteria→root exudates→bacteria→plant). Results from this research will elucidate the molecular mechanisms of interaction between root exudates and IAA-producing bacteria in the rice rhizosphere, thus helping us to further understand biological process in the rice rhizosphere and establish theoretical bases for sustainable development of green agriculture.