Cell and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture (CENA), University of Sao Paulo (USP), Piracicaba, Brazil.
Institute of Microbiology, Leibniz University Hannover, Hannover, Germany.
Sci Rep. 2016 Dec 15;6:38923. doi: 10.1038/srep38923.
For the last 150 years many studies have shown the importance of earthworms for plant growth, but the exact mechanisms involved in the process are still poorly understood. Many important functions required for plant growth can be performed by soil microbes in the rhizosphere. To investigate earthworm influence on the rhizosphere microbial community, we performed a macrocosm experiment with and without Pontoscolex corethrurus (EW+ and EW-, respectively) and followed various soil and rhizosphere processes for 217 days with sugarcane. In EW+ treatments, NO concentrations belowground (15 cm depth) and relative abundances of nitrous oxide genes (nosZ) were higher in bulk soil and rhizosphere, suggesting that soil microbes were able to consume earthworm-induced NO. Shotgun sequencing (total DNA) revealed that around 70 microbial functions in bulk soil and rhizosphere differed between EW+ and EW- treatments. Overall, genes indicative of biosynthetic pathways and cell proliferation processes were enriched in EW+ treatments, suggesting a positive influence of worms. In EW+ rhizosphere, functions associated with plant-microbe symbiosis were enriched relative to EW- rhizosphere. Ecological networks inferred from the datasets revealed decreased niche diversification and increased keystone functions as an earthworm-derived effect. Plant biomass was improved in EW+ and worm population proliferated.
在过去的 150 年中，许多研究表明蚯蚓对植物生长的重要性，但涉及该过程的确切机制仍知之甚少。许多对植物生长至关重要的功能可以由根际土壤微生物来完成。为了研究蚯蚓对根际微生物群落的影响，我们进行了一个巨观实验，分别有和没有 P. corethrurus（分别为 EW+ 和 EW-），并用甘蔗进行了 217 天的各种土壤和根际过程的跟踪。在 EW+处理中，地下（15 cm 深）的 NO 浓度和氧化亚氮基因（nosZ）的相对丰度在土壤和根际中较高，这表明土壤微生物能够消耗蚯蚓诱导的 NO。 shotgun 测序（总 DNA）表明，在 EW+和 EW-处理之间，土壤和根际中有大约 70 种微生物功能存在差异。总的来说，与 EW-处理相比，EW+处理中与生物合成途径和细胞增殖过程相关的基因更为丰富，这表明蚯蚓有积极的影响。在 EW+根际中，与植物-微生物共生相关的功能相对于 EW-根际更为丰富。从数据集推断出的生态网络表明，由于蚯蚓的影响，生态位多样化减少，关键功能增加。在 EW+中植物生物量增加，蚯蚓种群繁殖。
