种子微生物具有选择性地传递到植物下一代的可能性，且在植物初始群落形成中具有优先占位的优势，对植物的生长及健康至关重要。黄单胞菌是一类重要的植物病原菌，但糖黄单胞菌(Xanthomonas sacchari)迄今尚未发现致病性。本实验室从不同水稻品种、不同世代和不同地区分离到246株在种子中普遍存在的糖黄单胞菌，部分菌株基因组分析未发现与致病相关基因，且具有植物促生特性。因此，本项目将在前期工作基础上，以糖黄单胞菌这一特殊类群为研究材料，通过基因组MLST、SNPs等分析，结合荧光标记定位跟踪，在菌株水平上探究种子继代间的垂直传递、种子内生菌可能的来源和传播途径；并通过高通量测序及qPCR技术揭示接种该类群对水稻不同生长时期微生物群落的影响，探讨种子内生细菌的优先占位效应。通过上述研究，不仅为揭示植物与微生物互作机制和共进化理论提供实验依据，还将为植物有益微生物的合理利用提供新的资源和思路。

The seed microhabitat has received great attention recently for its potential as a reservoir and vector for beneficial microbes. It has been demonstrated that bacteria inhabiting seeds have the possibility of selectively transferred from one plant generation to another, and consequently act as the initial inocula for the plant microbiota. Seed-associated bacteria have the priority effects in initial assembly of plant microbiome. Xanthomonas is a well-known plant pathogenic bacterium, however, Xanthomonas sacchari hasn’t yet found pathogenicity. Moreover，plant beneficial characteristics, including the production of IAA, 1-aminocyclopropane-1-carboxylate (ACC) deaminase and siderophores, were found existing in some strains of X. sacchari. In our laboratory, 246 Xanthomonas sacchari strains were isolated from different rice varieties, different regions and different generations, which was the most common species in rice seeds. The genome analysis of some strains indicated that there was no the genes associated with disease-causing. Therefore, based on the previous results, this project will use X. sacchari as the experiment materials to explore the transmission model of seed endophytic bacteria as well as the role and function during germination, seedling development and plant growth. Genomic analysis and fluorescence labeling technologies will be used to verify the vertical transmission of seed endophytic bacteria on the level of strain. To discuss and clarify the niche pre-emption and modification of seed-borne endophytic bacteria, the effects of inculcation of X. sacchari on the microbial community structure of different tissues in rice during different growth periods will be detected through high-throughput sequencing and qPCR. The results of this project will be very helpful for us to further understand the mechanism of plant and microbial interactions and co-evolutionary theory. It will also provide novel strategies to capitalize on beneficial microbes for sustainable agroecosystems.