Zhou Xingang, Wang Zhilin, Jia Huiting, Li Li, Wu Fengzhi
Department of Horticulture, Northeast Agricultural University, Harbin, China.
Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, Northeast Region, Ministry of Agriculture, Harbin, China.
Front Microbiol. 2018 Apr 10;9:705. doi: 10.3389/fmicb.2018.00705. eCollection 2018.
Soil microbial communities have profound effects on the growth, nutrition and health of plants in agroecosystems. Understanding soil microbial dynamics in cropping systems can assist in determining how agricultural practices influence soil processes mediated by microorganisms. In this study, soil bacterial communities were monitored in a continuously monocropped Jerusalem artichoke (JA) system, in which JA was successively monocropped for 3 years in a wheat field. Soil bacterial community compositions were estimated by amplicon sequencing of the 16S rRNA gene. Abundances of ammonia-oxidizing and denitrifying bacteria were estimated by quantitative PCR analysis of the , , and genes. Results showed that 1-2 years of monocropping of JA did not significantly impact the microbial alpha diversity, and the third cropping of JA decreased the microbial alpha diversity ( < 0.05). Principal coordinates analysis and permutational multivariate analysis of variance analyses revealed that continuous monocropping of JA changed soil bacterial community structure and function profile ( < 0.001). At the phylum level, the wheat field was characterized with higher relative abundances of , , and , the first cropping of JA with , the second cropping of JA with , , , and . At the genus level, the first cropping of JA was enriched with bacterial species with pathogen-antagonistic and/or plant growth promoting potentials, while members of genera that included potential denitrifiers increased in the second and third cropping of JA. The first cropping of JA had higher relative abundances of KO terms related to lignocellulose degradation and phosphorus cycling, the second cropping of JA had higher relative abundances of KO terms nitrous-oxide reductase and nitric-oxide reductase, and the third cropping of JA had higher relative abundances of KO terms nitrate reductase and nitrite reductase. The abundances of genes decreased while increased in the third cropping of JA, continuously increased in the second and third cropping of JA ( < 0.05). Redundancy analysis and Mantel test found that soil organic carbon and Olsen phosphorus contents played important roles in shaping soil bacterial communities. Overall, our results revealed that continuous monocropping of JA changed soil bacterial community composition and its functional potentials.
土壤微生物群落对农业生态系统中植物的生长、营养和健康有着深远影响。了解种植系统中的土壤微生物动态有助于确定农业实践如何影响由微生物介导的土壤过程。在本研究中，对连续单作菊芋（JA）系统中的土壤细菌群落进行了监测，该系统中菊芋在一块麦田中连续单作了3年。通过对16S rRNA基因进行扩增子测序来估计土壤细菌群落组成。通过对amoA、nirS、nirK和nosZ基因进行定量PCR分析来估计氨氧化细菌和反硝化细菌的丰度。结果表明，菊芋单作1 - 2年对微生物α多样性没有显著影响，而菊芋第三次种植降低了微生物α多样性（P < 0.05）。主坐标分析和置换多元方差分析表明，菊芋连续单作改变了土壤细菌群落结构和功能概况（P < 0.001）。在门水平上，麦田的特征是变形菌门、放线菌门和酸杆菌门的相对丰度较高，第一次种植菊芋时芽单胞菌门相对丰度较高，第二次种植菊芋时浮霉菌门、绿弯菌门、芽单胞菌门和酸杆菌门相对丰度较高。在属水平上，第一次种植菊芋时富含具有病原体拮抗和/或促进植物生长潜力的细菌物种，而包括潜在反硝化菌的属的成员在菊芋第二次和第三次种植时增加。第一次种植菊芋时与木质纤维素降解和磷循环相关的KO术语相对丰度较高，第二次种植菊芋时与一氧化二氮还原酶和一氧化氮还原酶相关的KO术语相对丰度较高，第三次种植菊芋时与硝酸还原酶和亚硝酸还原酶相关的KO术语相对丰度较高。在菊芋第三次种植时amoA基因丰度下降而nirK增加，nirS在菊芋第二次和第三次种植时持续增加（P < 0.05）。冗余分析和Mantel检验发现，土壤有机碳和 Olsen 磷含量在塑造土壤细菌群落方面发挥着重要作用。总体而言，我们的结果表明，菊芋连续单作改变了土壤细菌群落组成及其功能潜力。
