摘要:为探明连续马铃薯、玉米单作及间作种植对土壤细菌群落组成的影响，利用IonS5TMXL高通量测序平台，分析了单作玉米（M）、单作马铃薯（P）、马铃薯||玉米间作（PM）下，土壤细菌群落组成以及多样性间的差异。结果表明：与单作相比，马铃薯||玉米间作土壤有机质含量显著升高（P < 0.05），但土壤全氮、碱解氮、全磷、速效钾、土壤pH等没有显著变化。所获得的56 787个土壤细菌可操作分类单元（OTUs）共分为46门、55纲、114目、208科、455属。土壤变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）和放线菌门（Actinobacteria）细菌占总相对丰度的57.68%~65.11%，为优势菌门；间作对土壤细菌群落多样性（香农指数、辛普森指数）、丰富度（ACE指数和Chao1指数）无显著影响，但改变了基于门、属水平上的细菌群落组成。与单作马铃薯相比，间作显著降低了土壤变形菌门（Proteobacteria）相对丰度（P=0.023），提高了浮霉菌门（Planctomycetes）的相对丰度（P=0.043）。在属水平上，相对丰度较低的芽单胞菌属（Gemmatimonas）、Candidatus Solibacter属更易受到种植方式的影响；间作提高了节杆菌属（Arthrobacter）、芽球菌属（Blastococcus）和芽孢杆菌属（Bacillus）的相对丰度。随细菌群落结构变化，细菌群落功能上出现差异，通过KEGG功能预测共得到7个一级功能层，35个二级功能层，表现出功能上的丰富性，土壤细菌群落在代谢、遗传信息处理和细胞过程方面功能活跃。7个一级功能层中的代谢功能组在马铃薯||玉米间作与马铃薯单作间有显著差异。利用前向选择，经蒙特卡罗检验表明，连续马铃薯、玉米单作及间作栽培5年后的土壤各理化性状指标与土壤细菌群落组成、多样性间的相关性均不显著。连续马铃薯||玉米间作及单作5年条件下土壤细菌群落组成的变化是由马铃薯||玉米间作作物种间互利和竞争关系而驱动的。
关键词:马铃薯||玉米间作/
细菌群落/
多样性/
功能预测/
高通量测序/
种间关系
Abstract:One of the reasons for the replanting problem in continuous potato cropping is the change in the soil microbial community structure. Many studies have shown that reasonable intercropping can alleviate replant disease, and the relationships of crop-soil-microorganisms are a hot topic in current agricultural ecosystem research. Therefore, the objective of this study was to examine the difference in the soil bacterial community composition after continuous potato and maize monoculture and intercropping. The IonS5TMXL high-throughput sequencing platform was used to analyze the soil bacterial community composition and diversity under maize monoculture (M), potato monoculture (P), and potato intercropped with maize (PM). The results revealed that soil organic matter significantly increased in the treatment of potato intercropped with maize (P < 0.05), when compared with the monocultures. However, there were no significant changes in the soil total nitrogen, available nitrogen, total phosphorus, available potassium, and pH among different treatments. Moreover, the total 56 787 Operational Taxonomic Units (OTUs) of bacteria were classified as 46 phyla, 55 classes, 114 orders, 208 families, and 455 genera. Proteobacteria, Acidobacteria, and Actinobacteria were the dominant phyla and accounted for 57.68%-65.11% of the total relative abundance of bacteria. The diversity index (Shannon-Wiener and Simpson) and the richness index (ACE and Chao1) of soil bacterial communities did not change; however, the relative abundance of the soil bacterial communities changed at the phylum and genus levels. Compared to the potato monoculture, the relative abundance of Proteobacteria decreased significantly after potato was intercropped with maize (P=0.023), while the relative abundance of Planctomycetes increased (P=0.043). Furthermore, Gemmatimonas and Candidatus Solibacter, with lower relative abundance, were found to be more easily influenced by the planting patterns. Moreover, intercropping increased the relative abundance of Arthrobacter, Blastococcus, and Bacillus. With the change in the bacterial community, the soil bacterial functions were separately classified into 7 and 35 functional categories at hierarchy level 1 and 2, respectively, using the KEGG function prediction, which implied abundant soil bacteria functions. From this, we garnered that soil bacteria were active in metabolic processes, genetic information processing, and cellular processes. Furthermore, the metabolic functional groups in the 7 primary functional layers had significant differences between potato intercropped with maize and potato monoculture (P=0.046). Additionally, forward selection of the soil environmental factors was used, and the result of the Monte Carlo test showed that there was no significant correlation between soil physicochemical and biological properties and the soil bacterial community composition and diversity after the five-year experiment. In conclusion, the relationship between the interspecific mutualism and competition in potato intercropped with maize was the driving factor of the change in the soil bacterial community.
Key words:Potato intercropped with maize/
Bacterial community/
Diversity/
Function prediction/
High-throughput sequencing/
Interspecific relationship
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