ASO诱导烟草根系分泌物和根际细菌在其防御体系构建中的作用

发布时间：2019-06-14 10:15

【摘要】：根系分泌物在调控植物与环境相互作用过程中发挥着至关重要的作用。虽然研究者对不同植物在不同生长期、不同生境中根系分泌物组成的变化及其对根际微生物的影响进行了大量的研究,但是对于根系分泌物如何影响根际微生物群落及微生物群落的改变给植物带来的影响却知之甚少。本文将植物与根际细菌作为一个系统,研究了经化学诱抗剂ASO(3-丙酮基-3-羟基吲哚的水分散粒剂,能诱导烟草对普通花叶病(Tobacco mosaic virus, TMV)和烟草白粉病(Erysiphe cichoracearum)的抗性)诱导处理后,烟草K326根系分泌物的组成变化及其对根际细菌群落组成和功能的影响,并通过对一株分离自植烟土壤的细菌的分类学地位、抗病性和趋化性等的研究,证明植物能通过根系分泌物吸引特定的根际细菌集聚。取得的主要结果如下：1、通过GC-MS和离子色谱分析了化学诱抗剂ASO诱导后烟草K326的根系分泌物中挥发性组份和有机酸的组成变化。结果表明,ASO诱导对根系分泌物中小分子物质的含量和有机酸组成无显著影响,但其显著改变了根系分泌物中小分子物质的组成。其中具有抗生素活性的脂肪酸3-甲基丁酸、2-甲基丁酸及具有杀虫活性的烟碱类衍生物麦斯明、新烟草灵和信号分子乙酰香草酮、乙酰丁香酮和靛红含量显著改变；这是根系分泌物直接影响根际微生物群落组成的物质基础和理论依据,同时也表明植物产生系统获得性抗性后会引发一系列的、广泛性的保护性反应。2、采用16S rDNA扩增子测序技术,对施用ASO处理的烟草K326根际细菌群落多样性及其功能的动态变化进行了研究。结果表明,K326根际微生物群落的多样性随植物的生长和ASO的施用减少。植物的生长时期对根际微生物群落的结构产生显著影响；ASO的施用则对K326根际微生物群落的结构、种群数量和功能产生影响,但是这一影响会随施用时间逐渐减弱。对根际细菌优势群落的组成及功能分析表明,在对照处理组中,根际优势细菌群落的已知功能主要是各类复杂有机物的降解和参与物质循环；而在ASO处理后,根际优势细菌群落的主要功能则转变为分泌抗生素和诱导植物系统抗性；从优势菌群的组成上看,ASO处理后,具有物质转换功能的菌群被具有防御功能的相关菌群所取代,从而使根际微生物群落的功能与植物的生存策略保持一致,进而得出根际微生物是植物适应环境的一个重要组成部分的结论。3、将ASO诱导后的K326根系分泌物作为选择性培养物,筛选得到一株具有二孢白粉菌(E. cichoracearum)抗性的细菌菌株,经形态学、生理生化、细胞化学和分子生物学鉴定该菌株为溶杆菌属的新种,命名为Lysobacter erysipheiresistens (RS-LYSO-3)。该菌株对ASO诱导后的K326根系分泌物表现出较强的趋化性,并在根际土壤中迅速繁殖,丰富度增加；生测实验表明RS-LYSO-3对烟草白粉病的防治效果明显。这些实验结果都提示着植物能通过根系分泌物成分的改变,招徕功能性的微生物,共同构筑防御系统,即烟草与其根际微生物能组成一个“共生体”以适应环境变化。
[Abstract]:Root exudates play a vital role in the regulation of the interaction between plants and the environment. Although the changes of root exudates in different habitats and different habitats of different plants and their effects on the rhizosphere microorganisms were studied, However, little is known about how the root exudates affect the microbial community and the change of the microbial community to the plants. In this paper, the plant and the rhizosphere bacteria were used as a system to study the water-dispersible granules of the chemical-induced ASO (3-acetone-3-hydroxy-1-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-3-hydroxy-1- The composition of the root exudates of tobacco K326 and its effect on the composition and function of the bacterial community in the rhizosphere and the taxonomic status, disease resistance and resistance of the bacteria isolated from the tobacco soil were studied, and it was proved that the plant was able to attract specific rhizosphere bacteria by root exudates. The main results were as follows:1. The composition of the volatile component and the organic acid in the root exudates of the tobacco K326 was analyzed by GC-MS and ion chromatography. The results showed that ASO induction had no significant effect on the content of small and medium-sized molecules in root exudates and the composition of small and medium-sized molecules in root exudates. wherein the fatty acid 3-methylbutyric acid,2-methylbutyric acid and the nicotine-like derivative with the insecticidal activity of the antibiotic activity are obviously changed; This is the material base and the theoretical foundation of the root exudates directly affecting the microbial community composition of the rhizosphere, and also shows that the acquired resistance of the plant will trigger a series of protective reactions, and the 16S rDNA amplicon sequencing technology is adopted. The diversity of bacterial community and its function in the rhizosphere of tobacco K326 treated with ASO were studied. The results showed that the diversity of the microbial community in the Rhizosphere of K326 decreased with the growth of plants and the application of ASO. The growth period of the plant has a significant effect on the structure of the rhizosphere microbial community; the application of the ASO has an effect on the structure, the number and function of the microbial community in the rhizosphere of the K326, but the effect will gradually decrease with the time of application. The composition and functional analysis of the bacterial dominant community in the rhizosphere indicated that in the control treatment group, the known function of the bacterial community in the rhizosphere is mainly the degradation of various complex organic matters and the participation of the material circulation, and after the ASO treatment, the main function of the bacterial community in the rhizosphere is transformed into the secretion of antibiotics and the induction of plant systemic resistance; after the ASO treatment, the bacteria group with the substance conversion function is replaced by the related flora with the defense function after the ASO treatment, so that the function of the rhizosphere microorganism community is consistent with the survival strategy of the plant, and then the rhizosphere microorganism is a conclusion of an important part of the environment of the plant, A bacterial strain with the resistance of E. cicum earum was selected, and the strain was identified as a new species of the genus Bacillus by morphological, physiological, biochemical, cytochemical and molecular biology, and was named Lysobacter sphaeirescens (RS-LYSO-3). The results showed that the control effect of RS-LYSO-3 on powdery mildew of tobacco was obvious. The results of these experiments show that the plants can change the components of the root exudates and attract the functional microorganisms to construct the defense system, that is, the tobacco and its rhizosphere microorganisms can make up a "symbiont" to adapt to the change of the environment.
【学位授予单位】：云南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S572

【相似文献】