杨树人工林根际土壤微生物群落组成及结构研究

发布时间：2018-01-01 18:42

本文关键词：杨树人工林根际土壤微生物群落组成及结构研究　出处：《山东农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：杨树(Populus spp.)是我国最重要的工业用材林树种之一,杨树人工林健康经营和长期生产力维持是林学和生态学研究的重要课题。基于细根与林分生产力的密切关系,杨树人工林细根研究亟需加强。树木根系是树木个体与土壤环境进行物质交换和能量运送的关键器官,林木根系与土壤环境间的互作效应对于双方以及根际环境的养分循环具有重要影响。根际土壤微生物作为重要的物质转化调节器在林木根土互作中发挥着关键作用。因此,研究根际土壤微生物对于了解和改善根际土壤微生物群落结构以及调节根际土壤养分循环具有重要意义。基于此,以欧美杨I-107(Populus×eurameicana‘Neva’)为研究对象,利用高通量测序技术准确分析了定殖在根际和非根际的细菌群落以及不同根序细根根际土壤细菌和真菌群落结构,并研究了不同根序根际土壤碳氮磷化学计量特征以及与根际土壤微生物群落的相关性,还筛选出土壤氮素循环相关菌,以期为深入探索林木根际土壤养分循环过程及根土互作关系提供更加科学的理论依据。本次研究发现:(1)根际和非根际细菌群落结构的比较,根际土壤包含145个细菌属,非根际土壤包含141个细菌属。根际和非根际相对丰度4%的属有8个,同一属的细菌类群在根际和非根际土壤中相对丰度存在显著差异(P0.05)。α多样性分析表明,根际土壤细菌群落多样性高于非根际土壤,但差异未达到显著水平。细菌群落排序结果较好地反映了土壤细菌群落从根际到非根际的变化和不同取样点的空间差异,根际效应对细菌群落差异的贡献率占21.2%。β多样性分析表明,杨树人工林根际和非根际土壤样品间细菌群落组成具有较大差异,根际和非根际土壤中各含有一些特有属(根际15个,非根际11个),此外还发现丰度发生显著变化的23个属,主要以纤维素降解菌和固氮菌为主。根系对根际微生物的选择是导致根际微生物群落组成和结构发生显著差异的重要机制,这将对根土界面碳氮循环产生显著影响。(2)不同根序土壤细菌和真菌群落结构比较,1-2级根、3级根和4-5级根根际土壤分别包含607个、593个和604个细菌属,128个、124个和130个真菌属。不同根序土壤细菌相对丰度1%的属有12个,其中,1-2级根土壤中Burkholderia菌属的丰度最高,其次是Bacteroides菌属;而Bacteroides属在3级根和4-5级根根际土壤中均为丰度最高的菌属;不同根序土壤真菌相对丰度1%的属有7个,其中,在1-2级根根际土壤中Trichosporon菌属的丰度最高,其次是Trichoderma菌属;在3级根根际土壤中Trichosporon属的相对丰度也是最高的;Aspergillus菌属在4-5级根中相对丰度最高。α多样性分析表明,从低级根到高级根土壤细菌群落的丰富度和多样性都在显著降低(P0.05),土壤真菌的丰富度和多样性变化不明显。对土壤样品的主成分分析表明,杨树人工林不同根序根际土壤间细菌群落组成存在较大差异。β多样性分析表明,杨树人工林不同根序间土壤细菌和真菌群落组成的相似性和差异性变化规律都正好相反。此外,随着根序等级的升高相对丰度显著上调的细菌属主要以抗酸性菌属和还原硝酸盐的菌属为主,显著下调的细菌属主要以固氮菌和生物降解菌为主。微生物群落在不同根序根际土壤中的变化提供了深入了解植物微生物相互作用,以及用于研究根际激发效应机制的新模式。(3)不同根序细根根际土壤碳氮磷化学计量特征及其与根际微生物多样性的相关性分析。杨树人工林根际土壤碳氮磷含量与非根际土壤存在显著差异(P0.05),但不同根序间速效氮、有效磷含量以及铵硝比未达到显著差异水平(P0.05)。根际土壤全碳含量随着根序升高显著下降,而全氮含量随着根序升高逐渐增加。1-2级细根根际土壤全磷含量显著高于4-5级根(P0.05)。杨树细根根际土壤C/N随着根序升高显著降低(P0.05);C/P随着细根序级升高逐渐下降,但在不同根序间差异不显著(P0.05)。土壤全碳和全氮含量及碳氮磷化学计量比均与细菌群落丰富性(chao指数和ACE指数)呈显著相关(P0.05),全磷含量与细菌群落相关性不显著。土壤碳氮磷化学计量与真菌群落多样性相关性不显著(P0.05)。杨树根际土壤碳氮磷养分循环呈现依赖于根序的变化特征,不同根序细根可能对微生物群落构建进行选择进而影响土壤碳氮磷循环过程。(4)通过对菌株的富集培养和分离纯化,在根际土壤中筛选到2株亚硝酸菌W31和W42,经分子系统学鉴定分别为Burkholderia cenocepacia strain AU1054和Burkholderia terrae strain KMY02,其最适发酵条件分别为底物氨氮浓度200 mg/L和300~500 mg/L时,pH值分别为7.5和8.5。
[Abstract]:Poplar (Populus spp.) is one of the most important industrial timber species in China, poplar forest health management and long-term maintenance of productivity is an important issue in forestry and ecology research. The close relationship between fine root and forest productivity based on the fine root of Poplar Plantation urgently strengthened. Tree roots are individual trees and soil environment are the key organs the exchange of material and energy transport, tree roots and soil environment interaction effect has important influence on both sides and rhizosphere nutrient cycling. Rhizosphere microorganisms as an important regulator of material transformation plays a key role in the tree root soil interaction. Therefore, the rhizosphere soil microbial research has important significance for understand and improve the soil microbial community structure in rhizosphere and regulate rhizosphere soil nutrient cycling. Based on this, by ofp0pulusxeuramericana I-107 (Populus * eurameicana 'Nev A ") as the research object, the accurate analysis of the colonization of bacterial communities in the rhizosphere and non rhizosphere and different order fine roots rhizosphere soil bacterial and fungal community structure using high-throughput sequencing technology, and study the correlation of different order roots rhizosphere soil carbon nitrogen and phosphorus stoichiometry and rhizosphere soil microbial community also, selected soil nitrogen cycling bacteria, in order to further explore the tree rhizosphere soil nutrient cycling processes and root soil interaction and provide a theoretical basis for more scientific. This research shows that: (1) compare the structure of rhizosphere and non rhizosphere bacterial communities in the rhizosphere soil, contains 145 bacterial genera in non rhizosphere soil, contains 141 bacterial genera. The rhizosphere and non rhizosphere relative abundance of 4% genera of 8, bacterial species of the same genus in rhizosphere and non rhizosphere soil in the relative abundance of significant differences (P0.05). Alpha diversity analysis showed that rhizosphere soil fine The diversity of bacterial communities was higher than that of non rhizosphere soil, but the difference was not significant. The bacterial community ordination results reflect the soil bacterial communities from the rhizosphere and non rhizosphere to change different sampling points of the spatial difference of rhizosphere effect on bacterial community differences in the contribution rate of 21.2%. beta diversity analysis showed that the samples poplar plantation rhizosphere and non rhizosphere soil bacterial community composition has great differences in rhizosphere and non rhizosphere soil contains some endemic genera (15 rhizosphere and non rhizosphere 11), in addition, abundance occurred in 23 genera of significant changes, to cellulose degrading bacteria and nitrogen fixation bacteria. Selection of roots on rhizosphere microorganisms may be an important mechanism of the composition and structure of rhizosphere microbial community had significant differences, the root soil interface of carbon and nitrogen cycles have significant effects. (2) of different order roots in soil bacterial and fungal community structure Comparison of 1-2 grade level 3 root and root, 4-5 root rhizosphere soil respectively contained 607, 593 and 604 bacterial genera, 128, 124 and 130 fungal genera. Different root orders of soil bacteria relative abundance of 1% of the 12 genera, the genus of 1-2 Burkholderia root in soil the highest abundance, followed by Bacteroides spp.; the Bacteroides is in grade 3 and grade 4-5 root root rhizosphere soil had the highest abundance of bacteria; soil fungi of different order roots relative abundance of 1% genera of 7, which, at the 1-2 level of Trichosporon in root rhizosphere soil bacteria abundance was highest, followed by Trichoderma fungi; relative abundance in grade 3 in root Rhizosphere soil of the genus Trichosporon is the highest; Aspergillus species relative abundance at the 4-5 level is highest in roots. Alpha diversity analysis showed that from lower to higher root root richness and diversity of soil bacterial community were significantly decreased (P0.05), the abundance of soil fungi Richness and diversity did not change significantly. The main component of soil sample analysis showed that the poplar plantation of different root orders between rhizosphere soil bacterial community composition differences. Beta diversity analysis showed that poplar root sequence between the composition of soil bacterial and fungal communities and the similarities and differences of the changes are just on the contrary. In addition, with the increase of relative abundance of root order significantly up-regulated bacteria mainly in the acid resistance of bacteria and nitrate reduction bacteria, significantly reduced the bacteria of the genus Azotobacter and mainly by biological degradation bacteria. Microorganisms provides in-depth understanding of plant microbe interactions in the rhizosphere of different order changes fall the root in the soil, as well as for the new model of rhizosphere priming effect mechanism. (3) different rhizosphere root order of soil carbon nitrogen and phosphorus stoichiometry and rhizosphere microbial diversity related Analysis. There were significant differences in Poplar Plantation rhizosphere soil carbon nitrogen and phosphorus content and non rhizosphere soil (P0.05), but not the same sequence between the available nitrogen, available phosphorus and ammonium nitrate ratio did not reach significant levels (P0.05). The rhizosphere soil total carbon content increased with root order was significantly decreased, and total nitrogen the content increased gradually with the root order of total phosphorus in.1-2 root rhizosphere soil was significantly higher than that of 4-5 (P0.05) C/N. The root root rhizosphere soil of Poplar with root order increased significantly decreased (P0.05); C/P with fine root level increased gradually decreased, but the difference between the different root order was not significant (P0.05). The total carbon and total nitrogen content and carbon nitrogen and phosphorus stoichiometry and bacterial community richness (Chao index and ACE index) were significantly correlated (P0.05), no significant correlation between total phosphorus content and bacterial community. No significant soil carbon nitrogen and phosphorus stoichiometry and fungal community diversity correlation (P 0.05). Poplar rhizosphere soil carbon nitrogen and phosphorus cycling showed variation depends on the root order, different order fine roots may choose to build on the microbial community affects soil carbon and nitrogen phosphorus cycle. (4) through the enrichment and purification of strains, screened 2 strains nitrite bacteria W31 and W42 in rhizosphere soil, the molecular phylogeny were identified as Burkholderia cenocepacia strain AU1054 and Burkholderia terrae strain KMY02, the optimum fermentation conditions were 200 mg/L and 300~500 substrate ammonia concentration mg/L, pH values were 7.5 and 8.5.

【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S714.3

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