Endophytic bacteria have attracted a great attention because they produce chemicals that increase the resistance of host plants against diseases. In the current study, 40 strains of endophytic bacteria from Kobreasia capillifolia of an alpine grassland were screened for the inhibitory effect against the tomato leaf pathogen Pseudomonas syringae. The endophytic bacterium strain 262XY2’ developed a clear inhibition zone of growth with a bacteriostatic band width of 0.67 cm against P. syringae on the cultural plates. The strain 262XY2’ also showed an inhibitory activity to Bipolaris sorokiniana, Stysanus stemonitis, Alternaria soloni, Botrytis cinerea, Fusarium solani and F. oxysporum. It was able to fix nitrogen, dissolve phosphorus and produce indole 3-acetic acid (IAA). Based on morphological characteristics and the molecular sequence analyses of 16S rRNA and gyrB genes, the 262XY2’ strain was identified as Bacillus subtilis. B. subtilis 262XY2’ strain tagged with the green fluorescence protein (GFP) was found to colonize stably in the roots, stems and leaves of tomato plants, and could be re-isolated from the rhizosphere soil after 0 to 60 days of inoculation. Moreover, it also exhibited a control effect of 48.55% against tomato leaf spot caused by P. syringae. Our results indicate that the antagonistic bacteria B. subtilis 262XY2’ has the potential to be used as a biocontrol agent for tomato leaf spot.

内生细菌引起了极大的关注，因为它们产生的化学物质可以增加宿主植物对疾病的抵抗力。在目前的研究中，筛选了40 株来自高山草原小圆叶内生细菌对番茄叶病原菌丁香假单胞菌 (Pseudomonas syringae)的抑制作用。内生细菌菌株 262XY2'在培养板上对丁香假单胞菌产生了明显的生长抑制区，抑菌带宽度为 0.67 cm 。菌株 262XY2' 也显示出对双极菌、茎干炎、黑链格孢、灰葡萄孢、Fusarium solani和F. oxysporum。它能够固氮、溶解磷并产生吲哚 3-乙酸 (IAA)。基于形态特征和16S rRNA和gyr B基因的分子序列分析，262XY2'菌株被鉴定为枯草芽孢杆菌。发现用绿色荧光蛋白 ( GFP )标记的枯草芽孢杆菌262XY2' 菌株在番茄植株的根、茎和叶中稳定定殖，并且可以在接种 0 至 60 天后从根际土壤中重新分离。此外，它还对丁香假单胞菌引起的番茄叶斑病表现出48.55%的防治效果。我们的结果表明，拮抗细菌B. subtilis 262XY2' 有可能用作番茄叶斑病的生物防治剂。