本文選題：土壤　切入點(diǎn)：根瘤菌　出處：《西北農(nóng)林科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：微生物在土壤的形成過程中發(fā)揮重要作用。然而,不同深度中的土壤微生物對生物和非生物環(huán)境擾動的響應(yīng)過程和多樣性變化仍不清楚。本文通過刺槐捕捉試驗(yàn)對楊陵農(nóng)田土壤0-300cm剖面(0-5、5-10、10-20、20-40、40-60、60-80、80-100、100-120、120-150、150-200、200-250、250-300 cm)12個層次土壤中的根瘤菌分布、系統(tǒng)發(fā)育進(jìn)行了研究,同時對置于花盆中的不同層次的土壤種植刺槐、三葉草以及澆水處理,通過土壤16S rRNA基因高通量測序分析,對擾動后土壤中微生物菌群結(jié)構(gòu)和變化進(jìn)行了研究。得到如下結(jié)果:通過刺槐捕捉試驗(yàn),從0-300cm土壤剖面中共分離到32株根瘤菌,其中0-100cm土壤分離到的菌株最多(占總數(shù)的90.6%)。16S rRNA序列分析表明,這些菌株屬于中慢生根瘤菌屬(Mesorhizobium)(30株),新根瘤菌屬(Neorhizobium)(2株)。持家基因recA-atpD-rpoB串聯(lián)基因系統(tǒng)發(fā)育分析,Mesorhizobium是優(yōu)勢菌(88%),包含一個已知種M.amorphae和三個未定種類群:Mesorhizobium sp.Ⅰ(占68.5%)、Mesorhizobium sp.Ⅱ(占6.25%)、Mesorhizobium sp.Ⅲ(12.5%)。菌株20-40-1和40-60-8與Neorhizobium galegae bv.orientalis HAMBI 540T系統(tǒng)發(fā)育關(guān)系最近,序列相似性為93.7%。在根瘤菌結(jié)瘤基因nodA、固氮基因nifH系統(tǒng)發(fā)育分析中,32株根瘤菌與Mesorhizobium聚類成一分支,說明與刺槐共生的根瘤菌的共生基因具有較強(qiáng)專一性。土壤理化在整個土壤剖面中呈現(xiàn)明顯的垂直變化,pH值隨著土壤深度的增加而增大但變化幅度很小(pH8.21-pH 8.42),土壤有機(jī)質(zhì)、總氮、速效鉀和速效磷含量均隨土壤深度的增加而降低。與原位土每個層次相比,種植刺槐后土壤中總氮的含量上升,C:N比降低。擾動后土壤16S rRNA高通量測序分析表明,微生物群落的多樣性隨著土壤深度的增加而降低,也呈現(xiàn)明顯的垂直空間分布。土壤理化性質(zhì)在微生物群落結(jié)構(gòu)組成中起重要作用,變形菌門相對豐度與土壤pH值呈顯著負(fù)相關(guān),土壤有機(jī)質(zhì)、總氮、有效鉀和磷含量對放線菌門、綠彎菌門、浮霉菌門相對豐度影響顯著。分析土壤中根瘤菌分布情況發(fā)現(xiàn),根瘤菌目是alpha-變形菌綱的優(yōu)勢菌,其中慢生根瘤菌科和葉瘤菌科相對豐度在擾動后有略微下降,種植刺槐后根瘤菌科相對豐度顯著上升。
[Abstract]:Microorganisms play an important role in soil formation. However, The response process and diversity of soil microorganisms to biological and abiotic environmental disturbances in different depths are still unclear. The distribution of rhizobia in 12 soil layers of Yangling farmland was studied in this paper. The distribution of rhizobia in 12 soil layers (0-300cm profile, 0-300cm profile, 5-1010-20C, 20-4040,60,80,80-100m, 100-120-120-1500-200200200-250250-300 cm) soil was studied, and the distribution of rhizobia in 12 soil layers was studied. Phylogeny was studied, and high throughput sequencing of 16s rRNA gene was carried out by planting Robinia pseudoacacia, clover and watering treatments in different layers of soil in flowerpots. The structure and changes of microbial flora in disturbed soil were studied. The following results were obtained: 32 strains of rhizobia were isolated from soil profile of 0-300cm by Robinia pseudoacacia capture test. In 0-100cm soil, the most strains were isolated (90.6%). 16s rRNA sequence analysis showed that, These strains belong to 30 strains of Mesorhizobium, and 2 strains of Neorhizobium. Phylogenetic analysis of recA-atpD-rpoB tandem gene phylogenetic analysis of Mesorhizobium, including a known species M. amorphae and three undetermined species: Mesorhizobium sp. 鈪，

本文編號：1643506