内生菌YN201728的定殖能力及其防治烟草白粉病的效果研究

为研究生防菌YN201728在烟草体内的定殖规律及防病机制,本研究利用其绿色荧光标记菌株YN28-P43GFPmut3a实时动态观测标记菌的定殖部位及密度,并探究其对温室烟草白粉病的盆栽防效与定殖的关系。结果表明,YN28-P43GFPmut3a发酵液处理烟草种子和幼苗后,种子内的标记菌含量可达2.18×10⁶ CFU·g^-1,在幼苗的根表土、根际土、根、茎、叶等组织中均能检测到标记菌,且其定殖密度表现为根表土>根际土>根>茎>叶。激光共聚焦显微镜观察显示,标记菌主要聚集在烟草根表皮、木质部导管、茎表皮、韧皮部及维管束组织、叶片表面和叶肉细胞间隙以及种皮与胚等部位。盆栽防效试验结果表明,YN201728野生型和标记菌株对烟草白粉病均有较好的保护和治疗效果,持效期长达21 d。此外,烟草叶片中内生菌的定殖量与其防效呈正相关。本研究结果表明,内生菌YN201728在烟草体内有良好的定殖和防治白粉病效果,具很好的开发潜力,为烟草病害的生物防治提供了一定的理论基础。

Colonization and Control Effect on Tobacco Powdery Mildew of Endophyte YN201728

To understand the colonization ability and mechanism of disease prevention of antibacterial YN201728 strain in tobacco, a green fluorescent gene labeled strain YN28-P43GFPmut3a was used to observe the colonization site and population of the endophyte dynamically in real time. Further, the relationship between the endophyte colonization and control effect of tobacco powdery mildew in greenhouse was investigated. The results showed that tobacco seeds and seedlings were treated with YN28-P43GFPmut3a fermentation broth, the labeled bacteria in the seeds was up to 2.18×10⁶ CFU·g^-1. The GFP-labeled endophyte was detected in root surface soil, rhizosphere soil, roots, stems and leaves of the seedlings, and its colonization density was shown as root surface soil>rhizosphere soil>root>stem>leaf. Confocal microscopy showed that the YN28-P43GFPmut3a mainly accumulated in root epidermis, xylem duct, stem epidermis, phloem and vascular bundle tissue, leaf surface and mesophyll cell gap, seed coat and embryo. The pot experiment revealed that the fermentation broth of YN201728 wild type and its GFP-tagged endophyte had good effects on preventing tobacco powdery mildew with validity up to 21 days. The colonization of endophytic bacteria is positively correlated with the control effect in tobacco leaves. We concluded that endophytic YN201728 had good ability in colonizing and controlling powdery mildew of tobacco and had good potential for development and utilization as biocontrol reagent, which providing a theoretical basis for biological control of tobacco diseases.