【作者】 高崇洋；

【导师】 祖元刚； 王文杰；

【作者基本信息】 东北林业大学 ， 植物学， 2006， 硕士

【摘要】 飞机草(Eupatorium odoratum)、薇甘菊(Mikania micrantha)和紫茎泽兰(E.adenophorum)为我国南方三种重要的菊科入侵物种,由于其具有繁飧能力强、生长势旺盛和根茎发达等特点,已经在我国云南、广东等局部地区对当地的农林牧业构成了严重威胁,引起了当地政府和国家的普遍关注。虽然对这些外来入侵种的化学防治已经取得了部分进展,然而大量施用化学药剂所带来的生态和环境问题,又使人们重新回到探求行之有效的生物防治方法之中。根际微生物是植物与土壤相互作用的重要媒介,可能与植物入侵具有重要关系,很多研究都已经表明外来种的成功入侵,极有可能是通过改变根际微生物群落结构来实现的,因此,通过分子生物学方法配合传统微生物学方法,对入侵植物的根际微生物群落结构进行深入研究具有重要的理论和实际意义。 为研究菊科入侵植物飞机草、薇甘菊和紫茎泽兰在入侵过程中对根际微生物群落的影响,以及通过我国特有树种一喜树替代紫茎泽兰生物入侵的可行性,采用了传统的培养技术对飞机草、薇甘菊、紫茎泽兰、喜树以及紫茎泽兰-喜树二者混栽根际中的真细菌和真菌进行了计数分析,同时应用PCR-单链构象多态性(SSCP)技术对根际中的真核微生物群落结构进行了相似性比较,采用末端限制性长度多态性(t-RFLP)技术分析土壤中真细菌群落结构的相似性,并针对喜树替代紫茎泽兰的可行性研究,构建了喜树根际真细菌微生物16S rDNA文库对喜树根际真细菌微生物的组成进行了调查。 结果表明,飞机草入侵地(E生境即优质生境和D生境即干扰生境)与非入侵地(F生境即脆弱生境(祖等,2002))具有相似的优势真细菌微生物种群,入侵地中真细菌绝对数量略高,但飞机草入侵大大降低了真核微生物群落的多样性和数量;薇甘菊入侵(E生境和D生境)降低了根际土壤中真细菌群落的多样性,但提高了其绝对数量,对真核类微生物影响较大,这种影响主要表现在浅层土的真核微生物群落结构的变化,薇甘菊浅层根系与地表凋落物是真核微生物群落结构的变化的主要因素。 在紫茎泽兰、喜树和二者混栽三种根际中,喜树根际土壤中真核微生物数量和种群多样性明显低于紫茎泽兰,喜树及混栽体系中由于含有喜树碱和羟基喜树碱而表现出了对真核微生物强烈的抑制作用:与此相比,喜树根际土壤中真细菌数量高于紫茎泽兰和混栽体系,而TRFLP分析表明在三根际中真细菌的多样性没有差别。紫茎泽兰的扩散和蔓延依赖于特有的真核微生物群落结构模式,并不改变真细菌群落的结构,喜树能够通过根系分泌物改变紫茎泽兰入侵性的真核微生物群落结构模式,进而制约其外延。 对喜树根际真细菌16S rDNA文库测序比较分析,包含了10个已分类的门,其中Proteobacteria门为优势菌群,占24.71%(其中δ-Proteobacteria占17.65%),Acidobacteria门占16.47%,Bacteroidetes门占10.59%,另外还有12.94%未分类菌,喜树根际微生物群落表现出了较为丰富的多样性。更多还原

【Abstract】 Eupatorium odoratum, Mikania micrantha and E. adenophorum are three serious exotic composites in South of China. Because of high seed-production, strong growth and developed rhizoma, the three plants have widely distributed in Yunnan and Gongdong provinces and directly threatened the local agriculture, forestry and farming and absorbed local government and nation’s attention. Utilization of many chemicals to control the invaders has brought out more ecological and environmental problems. This drives us to seek more efficient and lower pollutant techniques to control the invaders. Rhizospheric microbes are the important media between plants and soil and maybe relate to exotic plant invasion. Some researches had demonstrated that exotic plants invaded successfully by changing the rhizoshperic microbial structure. Therefore, it is very important in theory and practice to demonstrate the ambitious invading microbial pattern in detail.In order to investigate the impacts of E. odoratum, M. micrantha and E. adenophorum on the rhizospheric microbial community and the possibility that utilization of happy tree, Camptotheca acuminata controls E. adenophorum, traditional culture-dependent counting method and culture-independent small-subunit-ribosomal RNA gene-targeted molecular techniques(16sRDNA), PCR-Single-Strand Conformation Polymorphism (SSCP), terminal Restrain Fragment Length Polymorphism(TRFLP) combined with 16S rDNA library, were adopted to compare the composition and structure of Fungi and Bacteria in the rhizospheres.Results showed that rihzoshpere of E. odoratum had the similar dominant bacterial population in invading zones (E habitat, i.e. Excellent site for the growth of this species and D habitat, i.e. Disturbed site where vegetative growth is slightly depressed while reproductive growth is strongly accelerated) and naked soil (F habitat, i.e. Fragile site where the vegetative and reproductive growth of this weed are abruptly depressed. The detail of this classification can be found in Zu et al, 2002), but it decreased obviously the eukaryotic diversity and quantity. In the case of M. micrantha, bacterial population in the invading zones (E and D habitats) was lower than that in the naked soil (F habitat), while the quantity was improved. The influences on eukaryotic diversity was much stronger comparing to bacteria, moreover, it decreased obviously their quantity. Therefore, M. micrantha dramatically influenced on the eukaryotes, especial on the eukaryotic structure in the surface soil, which maybe was mainly caused by the shallow root system of M. micrantha or the litter fall on soil surface.Counting results indicated the numbers of Bacteria increased in turns in rhizospheres of E adenophorum, mixed plantation and C. acuminata, while that of fungi decreased in turns. PCR-SSCP profiles showed eukaryotic microbial community in rhizosphere of C. acuminata was lower than that of E. adenophorum and mixture plantation. TRFLP analysis on Bacteriashowed no difference among 3 rhizospheres, and the sequences of 16S rDNA clone library from Ca rhizospheres distributed in 10 known phyla, in which phylum Proteobacteria was the absolute dominant group and accounted for 24.71% of cloned sequences (5-Proteobacteria accounted for up to 17.65%), and phyla Acidobacteria and Bacteroidetes accounted for 16.47% and 10.59% of cloned sequences respectively. In addition, high performance liquid chromatography checked out a trace amount of camptothecin and hydroxycamptothecin in the rhizospheric soil of C. acuminata and mixture plantation, but examined no either camptothecin or hydroxycamptothecin in rhizospheric soil of E. adenophorum. Therefore, invasion and diffusion of E. adenophorum evidently depended on distinctive eukaryotic community structure mode, but not on the bacterial mode. And C. acuminata was able to alter the invasive eukaryotic community structure mode of E. adenophorum by secreting camptothecin and hydroxycamptothecin into rhizospheres, and further inhitibited overspread of Ea. This study provided rhizospheric theoretic evidence for substituting C. acuminata for E. adenophorum.更多还原