中文摘要：

为了探索甘蔗固氮菌DX120E菌株侵入根的方式以及菌株在甘蔗植株内的定殖规律, 确定人工接种固氮菌适宜的侵染浓度和定殖特点, 采用绿色荧光蛋白（GFP）标记的固氮菌DX120E接种甘蔗组培苗, 以荧光显微镜观察其侵染和定殖情况, 以抗生素抗性标记法和平板分离计数法测定DX120E菌株的种群动态。结果表明, 菌株DX120E在2个甘蔗品种的根、叶鞘和叶内均能定殖, 定殖菌量依次均为根〉叶鞘〉叶; 不同接种浓度下, 最大定殖数量无显著差异, 1×10^2 CFU mL–1的接种量足够侵入甘蔗并积累定殖。DX120E从甘蔗根表面的裂隙、主根和侧根发生处及根的断裂处均可侵入, 主要在根表面细胞间隙和细胞内大量定殖, 同时也可迁移到叶片的叶肉细胞和维管束细胞中定殖。

英文摘要：

To explore the invasion patterns of N2-fixing bacteria strain Klebsiella sp. DX120E and its colonization in sugarcane, and to determine the optimum concentrations of inoculum, we inoculated tissue culture seedlings of two sugarcane varieties （GT21 and B8） with different concentrations of Klebsiella sp. bacteria strain DX120E labeled by green fluorescent protein （GFP） gene, and with ddH2O as CK. The results showed that the strain DX120E propagated in root, leaf sheath and leaf of sugarcane seedlings, and bacteria quantities in different parts were root 〉 leaf sheath 〉 leaf. There were no differences in the maximum propagation quantity under various inoculating concentrations, with the optimum concentration of 1×10^2 CFU mL–1.Fluorescence microscope observation indicated that the bacteria could invade root through the surface cracks, generating sites of main root and lateral root, and root fracture, and intensively propagate in intercellular spaces and cells of the root, also transfer to mesophyll cells and vascular bundle sheath cells in leaf.