不同作物根际土壤微生物的群落结构特征分析

为探究根际微生物群在支持植物生长、发育和健康方面的重要作用,本研究在2017年7月采集同一农田中大豆Glycine max (L.) Merr.]、玉米Zea mays)、花生(Arachis hypogaea L.]、四季豆Phaseolus vulgaris L.]、豇豆Vigna unguiculata (L.) Walp]、番薯Ipomoea batatas (L.) Lam.]和芋艿Colocasia esculenta (L.) Schoot]7种不同作物,通过Illumina MiSeq测序技术和磷脂脂肪酸(PLFA)对这7种不同作物的根际微生物群落结构和组成进行了分析。结果显示,不同作物根际土壤微生物的PLFA种类和组成差异显著,但均以表征革兰氏阴性菌、革兰氏阳性菌和真菌的特征脂肪酸为主。花生根际土中微生物的PLFAs含量最高,花生根际土中的真菌细菌比(F/B)显著高于其他作物,且其革兰氏阳性菌与革兰氏阴性菌比(G⁺/G^-)最低。尽管在门水平,变形菌门、放线菌门、酸杆菌门和厚壁菌门是7种作物根际微生物的主要优势门,但是在纲水平和目水平不同作物根际微生物组成存在差异。Alpha多样性分析表明,大豆根际的OTU丰富度(Chao1,P<0.001)和细菌群落多样性(Shannon,P<0.001)在7种作物中最高。非度量多维尺度分析(NMDS)表明,根际微生物群落结构在OTU和PLFAs水平下均以不同作物形成聚类,不同聚类间的差异显著。根际敏感微生物的筛选和比较进一步说明不同作物对根际微生物的选择具有差异性,群落中某些特定菌群优势度存在区别,不同作物具有不同敏感微生物的选择倾向。本研究为构建健康的植物根际微生物群落以促进植物育种提供了基础。

Characteristics of Microbial Community Structure in the Rhizosphere Soil of Different Crops

The Rhizobacteria plays a crucial role in plant growth, development and health. In this study, rhizosphere soils of seven different crops, including soybean Glycine max (L.) Merr.], maize (Zea mays), peanut (Arachis hypogaea L.), kidney bean (Phaseolus vulgaris L.), cowpea Vigna unguiculata (L.) Walp], sweet potato Ipomoea batatas (L.) Lam.] and cocoyam Colocasia esculenta (L.) Schoot], were collected in July 2017 to explore the effects of crop taxa on rhizosphere microbiomes. Illumina MiSeq sequencing and phospholipid fatty acid (PLFA) were used to investigate the microbial community structure and diversity of rhizosphere soil. The difference in microbial PLFA biomarker contents among different crops were observable. Compared with the other crops, the total PLFAs and the biomass ratio of fungi and bacteria (F/B) in the rhizosphere soil of peanut were the highest, whereas the biomass ratio of gram positive bacteria and gram negative bacteria (G⁺/G^-) was the lowest. Although the seven groups had similar dominant phyla, such as Proteobacteria, Actinobacteria, Acidobacteria and Firmicutes, their bacterial compositions at the class and order level were obviously different. Alpha diversity analysis showed that the OTU richness (Chao1, P <0.001) and bacterial community diversity (Shannon, P <0.001) in the rhizosphere of soybean was the highest among the seven crops. Non-metric multidimensional scale analysis (NMDS) revealed that the rhizosphere microbial community structure formed significant clustering with different crops under OTU and PLFAs levels. The screening and comparison of sensitive microorganisms in the rhizosphere further showed that crops had distinctive selection of the rhizosphere bacterial community and species-sensitive microorganism. These results indicated that the rhizosphere microbiome was correlated with crop taxa. This study can provide a basis on which to construct a healthy plant rhizosphere microbiome to improve plant breeding.