【作者】 李林；

【导师】 黎定军；

【作者基本信息】 湖南农业大学 ， 烟草科学与工程技术， 2012， 硕士

【摘要】 烟草是重要的经济作物,我国是世界上烟草种植面积和烟叶产量最大的国家；烟草黑胫病与烟草青枯病是烟叶生产的两大土传性病害,在我国南方烟区常混合发生,对烟叶的优质和安全生产造成严重危害。生防菌X23分离自烟草根际土壤,经16S rDNA系统发育分析,确定为短短芽孢杆菌(Brevibacillus brevis X23)。此属的细菌可分泌大量的抑菌活性物质,被认为具有开发为优良生防菌的潜力,因而越来越受到植保科技工作者的青睐。本论文先在实验室进行生防菌B.brevis X23与烟草黑胫病菌及烟草青枯菌的平板对峙试验；再分别开展温室盆栽试验与大田生防试验,研究B.brevis X23在特定条件与自然环境下,对烟草黑胫病及青枯病的防治效果,为生防菌X23的推广应用提供参考。在上述研究的基础上,本论文研究了生防菌B.brevis X23对烟草青枯病菌和黑胫病菌的作用机理。结果表明,X23的外泌抗菌肽可以破坏青枯病菌的细胞质膜,导致细胞内容物渗漏,最终杀死青枯病菌；与其抑菌细菌的作用机理相似,X23分泌的抗菌肽还可以导致黑胫病菌的细胞膜破裂,在光学显微镜(1000倍)下可观察到明显的质壁分离。为了克隆X23外泌抗菌肽的编码基因,本论文还构建了X23基因组的精细图谱,对B.brevis X23全基因组进行了生物信息学分析,从中挖掘出了6个非核糖体合成抗菌肽的编码基因簇。这些发现为B.brevis X23的遗传改良奠定了基础。更多还原

【Abstract】 Tobacco is an important economic crop,China is the largest tobacco acreage and production country in the world.Tobacco black shank and bacterial wilt are the two soil-borne diseases of tobacco production,They often mixing occur in southern area of China,cause serious harm to tobacco quality and safety.The biocontrol bacteria X23isolated from the rhizosphere soil of tobacco,and then identified as Brevibacillus brevis X23by16S rDNA phylogenetic analysis. Bacteria of this genus can secrete large amounts of antibacterial substances,is considered to have the potential to develop a good biocontrol strain,therefore,they increasingly favored by plant protection science and technology workers.In this paper,firstly,conducted the test of biocontrol bacteria B.brevis X23against phytophthora parasitica var. nicotianae (breda de haan) tucker and Ralstonia soanacearum E F Smith on plate in the laboratory.Then,respectively,developed greenhouse pot experiment and field biocontrol tests,to study the biocontrol effect of B.brevis X23prevent tobacco black shank and bacterial wilt in the specific condition and natural environment,which provided a reference for biocontrol bacteria X23’promotion and application.On the basis of the above study,this paper studied the mechanism of action of B.brevis X23against phytophthora parasitica var. nicotianae (breda de haan) tucker and Ralstonia soanacearum E F Smith.The results showed that X23’s secreted antimicrobial peptide could destroyed the plasma membrane of Ralstonia soanacearum E F Smith,resulted in the leakage of cell contents,and ultimately kill the R.solanacearum.Similar to the mechanism of action of it inhibited bacteria,the secreted antimicrobial peptide of X23could also cause phytophthora parasitica var. nicotianae (breda de haan)tucker’smembrane rupture,and under an optical microscope (1000times),the obvious plasmolysis could be observed.In order to clone the encoding gene of X23’s secreted antimicrobial peptides,the paper also build B.brevis X23’s genome fine map,bioinformatic analyzed the whole genome of X23,then diged out of the six non-ribosomal synthesis of antimicrobial peptides encoding gene cluster. These findings lay the foundation for the genetic improvement ofB.brevisX23.更多还原