KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 咪唑乙烟酸对拟南芥代谢及其微生物群落结构的影响 | |
| Alternative Title | Effects of imazethapyr on Arabidopsis metabolism and microbial community structure |
| 刘婉月 | |
| Subtype | 硕士 |
| Thesis Advisor | 钱海丰 ; 潘响亮 |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 工程硕士 |
| Keyword | 咪唑乙烟酸 手性除草剂 微生物群落 根际分泌物 对映体选择性 Imazethapyr Chiral Herbicide Microbial Community Root Exudates Enantioselectivity |
| Abstract | 除草剂咪唑乙烟酸 (IM) 因其高效的除草活性， 被而全世界范围内广泛使用。 IM 是一个典型的手性除草剂， 分为 R 型咪唑乙烟酸 (R-IM) 和 S 型咪唑乙烟酸 (S-IM)。 除草剂的使用， 不可避免造成其在土壤和叶面的残留， 影响植物的生长和代谢， 同时影响叶面和根际微生物。 本论文以模式植物拟南芥为研究对象， 应用 16S rRNA 基因测序和代谢组学等手段， 研究 IM 喷洒和土壤残留情况下， 拟南芥的生理反应、 根际分泌物和叶面代谢物的变化及植物叶际、 根际微生物的变化， 从而深入评估除草剂的环境风险，加深对植物代谢与微生物组之间的联系。研究结果表明， 拟南芥表面喷洒 35 g/ha 咪唑乙烟酸外消旋体 (Rac-IM) 对拟南芥生长有明显的抑制作用。 处理 7 天及 14 天后， 拟南芥的鲜重抑制率分别为 52％和 74％； 此外， Rac-IM 处理可降低叶面含水率，破坏叶面细胞结构，降低植物光合效率和抗氧化酶的活性，尤其是改变叶际微生物群落组成结构。Rac-IM 处理拟南芥 14 天后， 植物或人类致病属 Pseudomonas 和 Sphingobium 的相对丰度有所增加，表明喷洒 Rac-IM 可能增加叶面上定殖的潜在致病细菌相对丰度。 在土壤中加入 133 μg/(Kg dry soil) IM 对映体也可以影响植物生长和根际微生物的群落。 R-IM 处理后 7 天， 植物鲜重抑制率达到 16.2%， 植物含水量和光合效率也同时降低或显著抑制， 而 S-IM 处理组与对照组无显著差异。这些结果表明与 S-IM 相比， R-IM 对拟南芥有更强的植物毒性。除此之外， IM 对映体改变了拟南芥根际分泌物组成和根际微生物群落结构， 具体表现为 R-IM 诱导的根际分泌物水平高于对照，包括大多数糖类，氨基酸类和有机酸类。 研究还表明一些可能的有益菌如 Ramlibacter 和 Bacillus 在根际被富集， 或许与植物抵抗胁迫有关。 通过对根际微生物的相对丰度与根际分泌物的相关性分析发现， 只有一种根际分泌物 (有机酸： 3-羟基丁酸) 与有益根际微生物 Ramlibacter 呈正相关，表明该有机酸可能作为 Ramlibacter 的碳源。 R-IM 处理增加了该有机酸分泌量，也因此招募更多 Ramlibacter 提高植物抗胁迫能力。 研究表明， IM 的手性差异体现在对植物代谢产物的手性选择性上，从而塑造了不同的根际微生物群落。残留于土壤中的 IM 对映体对根际微生物及根际分泌物有着直接作用，而对植物叶际微生物和植物叶面代谢系统则会产生一些间接影响。结果表明，土壤中IM 对映体的残留也可以显著影响叶面代谢物。 R-IM 的土壤残留可使大多数糖类含量升高，例如半乳糖和果糖； 而 S-IM 处理下氨基酸类含量均有所降低。此外，IM 对映体还改变叶际微生物群落结构。 叶际微生物与叶面代谢相关性分析表明，IM 处理下几种氨基酸类代谢产物含量下调，从而导致微生物可利用氮源减少；同时具有固氮能力的微生物包括 Xanthobacteraceae, Rhizobiaceae, Azospirillaceae,和 Burkholderiaceae，形成微生物群落并成为优势微生物。本研究结果证实， 无论是直接喷洒 IM 或是土壤中残留 IM，都对拟南芥生长有抑制作用，改变其生理特征，并且改变根际和叶际微生物群落结构。土壤中残留的 IM 对映体直接作用于植物根际，改变根际分泌物组成以及根际微生物群落结构，并且间接影响叶面代谢系统及叶际微生物群落结构。 这项研究帮助我们深入了解了除草剂 IM 在环境中的对映体选择性， 了解植物微生物组与代谢系统之间的联系， 并为手性除草剂应用提供证据。 |
| Other Abstract | The herbicide imazethapyr (IM) is widely used worldwide due to its high activity. IMis a typical chiral herbicide which is divided into R-imazethapyr (R-IM) andS-imazethapyr (S-IM). The use of herbicides inevitably causes residues in the soil andphyllosphere, which affects the growth and metabolism of plants, as well as thephyllosphere and rhizosphere microbes. In this paper, the model plant Arabidopsisthaliana was used as the research object, 16S rRNA gene sequencing andmetabolomics were used to study the physiological response of A. thaliana, thechanges of root exudates and leaf metabolites, and the changes of microbes in thephyllosphere and rhizosphere of A. thaliana under IM spraying and soil application.With a view to in-depth assessment of the environmental risks of herbicides and todeepen the understanding of the link between the metabolic system and themicrobiome.The results showed that spraying 35 g/ha IM racemate (Rac-IM) on the surface of A.thaliana significantly inhibited the growth of plant. After 7 and 14 days of treatment,the fresh weight inhibition rate of A. thaliana is 52%, 74% respectively; in addition,Rac-IM reduced the water content of the leaves, destroyed the cell structure, reducedthe photosynthetic efficiency and antioxidant enzyme activity of the plant, especiallychanged the leaves microbial community. After 14 days of Rac-IM treatment in A.thaliana, the relative abundance of Pseudomonas and Sphingobium increased as apotential plant or human pathogenic genus, indicating that spraying Rac-IM mayresult in an increase in the relative abundance of potential pathogenic bacteria on theleaves. The results of adding 133 μg/(Kg dry soil) IM enantiomer to the soil showedthat after 7 days under R-IM treatment, it was found that the inhibition rate of plantfresh weight reached 16.2%, which also significantly inhibited the plant moisturecontent and photosynthetic efficiency, while there was no significant differencebetween the S-IM treatment group and the control group. These results indicate that R-IM has a stronger inhibitory effect on plants than S-IM. In addition, the IMenantiomer in the soil can also change the community structure of the A. thalianarhizosphere microbes and the composition of root exudates. Specifically, the R-IMtreatment induced the content of root exudates are higher than control group,including most sugars, amino acids and organic acids. Some potentially beneficialmicrobes such as Ramlibacter and Bacillus are enriched in the rhizosphere forprotection plants resist stress, especially after R-IM treatment. By analyzing thecorrelation between the relative abundance of rhizosphere microbes and the content ofroot exudates, we observed that there was only one organic acid, 3-hydroxybutyricacid, positively associated with the beneficial rhizosphere microbe Ramlibacter,indicating that this organic acid may be a carbon source for Ramlibacter. R-IMtreatment increased the secretion of 3- hydroxybutyric acid, so it recruited moreRamlibacter to improve the plant's resistance to stress. Studies have shown that thechiral differences in IM are reflected in the chiral selectivity to plant metabolites,thereby shaping different rhizosphere microbial communities. The IM enantiomersremaining in the soil have a direct effect on rhizosphere microbes and root exudates,while it has indirect effects on plant leaf microbes and plant metabolism. The resultsshowed that IM enantiomer in the soil had a significant effect on the leaf metabolitecontent. The content of most sugars increased under R-IM treatment, such asgalactose and fructose, while the content of amino acids decreased under S-IMtreatment. In addition, the residual enantiomer in the soil also changed the leafmicrobial community structure. Analysis of the correlation between phyllospheremicrobes and leaf metabolism showed that the content of several amino acidmetabolites was reduced under IM treatment, resulting in a reduction in the nitrogensource available to the microbes; meanwhile, microbes with nitrogen-fixingcapabilities including Xanthobacteraceae, Rhizobiaceae, Azospirillaceae, andBurkholderiaceae formed the microbial community has become the dominantmicrobes.The results of this study confirmed that whether spraying Rac-IM directly or applyingthe IM enantiomer in the soil had an inhibitory effect on the growth of A. thaliana,changed its physiological characteristics, and altered the phyllosphere microbialcommunity structure. The IM enantiomer in the soil directly acts on the plantrhizosphere, changes the composition of root exudates and rhizosphere microbialcommunity structure, and indirectly acts on the leaves to cause changes in the leafmetabolic system and phyllosphere microbial community structure. This study helpedus improve our understanding of the differences in IM toxicity, understand the linkbetween plant phyllosphere and rhizosphere microbes and metabolic system, andprovide strong evidence for the application of chiral herbicides. |
| Subject Area | 环境工程 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15436 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 刘婉月. 咪唑乙烟酸对拟南芥代谢及其微生物群落结构的影响[D]. 北京. 中国科学院大学,2020. |
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