中文摘要：

在水培和土培条件下利用激光共聚焦扫描显微镜（confocal laser scanning microscopy,CLSM）和扫描电子显微镜（scanning electron microscopy,SEM）研究绿色荧光蛋白（green fluorescence protein,GFP）标记的解淀粉芽孢杆菌SQR9（SQR9-gfp）菌株在香蕉根表的定殖情况。结果表明：在接种后2~8 d,SQR9-gfp可在香蕉根表有效定殖并形成微菌落,定殖主要发生在主根的分生区和伸长区、侧根、主根与侧根的交界处以及根毛区,而附着于根尖的细菌数量很少。2种系统下SQR9-gfp的定殖表型相似,表明水培等限制系统可在短期内模拟真实的土培条件。对SQR9-gfp的定量计数结果表明：接种4 d后其在香蕉根表的密度保持在105~106CFU·g^-1,以及在根际土中密度为106~107CFU·g^-1,接种15 d后细菌密度略有下降。结论：SQR9能在香蕉根表有效定殖并在根际保持一定浓度,可为进一步利用该PGPR菌株防控香蕉枯萎病提供理论基础。

英文摘要：

Efficient colonization of plant growth-promoting rhizobacteria（ PGPR） on plant roots is crucial for the exertion of the growth promotion and biocontrol effects. This study was performed to investigate the colonization patterns of Bacillus amyloliquefaciens SQR9 on banana roots to understand its application prospect on plant growth and biological control. The colonization patterns of B. amyloliquefaciens SQR9 tagged by green fluorescence protein（ GFP） on banana roots was investigated in hydroponic and natural soil system by confocal laser scanning microscopy（ CLSM） and scanning electron microscopy（ SEM）. The results showed that SQR9 carrying gfp（ SQR9-gfp） could effectively colonize on banana roots and formed micro-colonies at 2 to 4 days of inoculation. The colonization of bacterial cells mainly occurred on the differentiation and elongation zones of the main roots,the lateral roots,junctions between roots and the root hairs,while few labeled bacterial cells were detected to attach along the root tips. In addition,similar colonization patterns of SQR9-gfp were obtained under both systems suggested that the hydroponic system could represent the natural soil system in a short time. The quantitative analysis revealed that at 4 days after inoculation,the population of SQR9-gfp was maintained at about 105-106CFU·g^-1roots,and 106-107CFU·g^-1soil,respectively; While the abundance of SQR9 slightly decreased at15 days post inoculation. Conclusions： SQR9 could effectively colonize on banana roots and reach the appropriate population,which could provide the theoretical basis for the practical application of SQR9 for suppression of banana wilt.