辣椒连作对土壤细菌群落的影响

【目的】土壤微生物对农业生态系统的长期可持续性至关重要。为探讨不同连作年限对辣椒土壤细菌群落结构和潜在功能的影响。【方法】采用16S rRNA基因高通量测序PICRUSt功能预测相结合的研究方法,对不同连作年限下(1Y、3Y、5Y和10Y)的辣椒土壤细菌微生物群落结构和功能进行分析。【结果】微生物多样性指数和共生网络复杂度随连作年限的延长而降低,同时,连作年限变化对细菌群落组成有显著影响。不同的土壤细菌种群对连作措施的响应程度不一,长期连作增加了变形菌门和拟杆菌门的相对丰度,但降低了绿弯菌门、酸杆菌门、厚壁菌门和髌骨细菌门的相对丰度。PICRUSt功能预测结果表明,延长连作年限改变了土壤细菌整体的氮、磷代谢能力,导致细菌群预测功能基因发生了变化,能量代谢、氨基酸代谢和碳水化合物代谢等重要代谢功能基因减少,而折叠、分类和降解、复制和修复、膜转运、细胞生长与死亡等功能基因丰度明显增加。冗余分析表明,土壤有机质和有效磷是影响细菌群落迁移和功能变化的关键土壤理化因子。【结论】延长辣椒连作年限后,细菌群落结构改变和多样性下降导致土壤微生物群落功能失调可能是造成辣椒连作障碍的原因之一。

Effect of continuous cropping of hot pepper on soil bacterial community

Objective] Soil microorganisms are essential for the long-term sustainability of agricultural ecosystems. This study aims to explore the effects of continuous cropping of hot pepper on the structure and function of soil bacterial community. Methods] We employed high-throughput sequencing of 16S rRNA and PICRUSt-based functional prediction to investigate the bacterial abundance, diversity, community composition, and potential functional component in the soils with continuous cropping of hot pepper for 1, 3, 5, and 10 years (1Y, 3Y, 5Y, and 10Y, respectively). Results] The Shannon index and co-occurrence network complexity of soil bacteria decreased with the extension of continuous cropping years. The bacterial community structure was markedly affected by the years of continuous cropping, and different bacterial populations had varied responses to continuous cropping. Long-term continuous cropping increased the relative abundance of Proteobacteria and Bacteroidetes, while decreasing that of Chloroflexi, Acidobacteria, Firmicutes, and Patescibacteria. Furthermore, PICRUSt-based functional prediction showed that the continuous cropping changed the overall nitrogen and phosphorus metabolism of soil bacteria. After long-term continuous cropping, the functional genes in energy metabolism, amino acid metabolism, and carbohydrate metabolism showed reduced relative abundance, while those involved in folding, classification and degradation, replication and repair, membrane transport, and cell growth and death had increased relative abundance. The results of redundancy analysis indicated that soil organic matter and available phosphorus were the key factors associated with the migration and functional changes of soil bacteria. Conclusion] After long-term continuous cropping of hot pepper, the change of community structure and the decline of diversity to the dysfunction of soil microbial community, which may be one of the reasons for the continuous cropping obstacles of hot pepper.