Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, 13400-970, Brazil.
Department of Land, Air and Water Resources, University of California - Davis, Davis, CA 95616, USA.
FEMS Microbiol Ecol. 2019 Mar 1;95(3). doi: 10.1093/femsec/fiz009.
The conversion of native forest to agriculture is the main cause of microbial biodiversity loss in Amazon soils. In order to better understand this effect, we used metagenomics to investigate microbial patterns and functions in bulk soil and rhizosphere of soybean, in a long-term forest-to-agriculture conversion. Long-term forest-to-agriculture led to microbial homogenization and loss of diversity in both bulk soil and rhizosphere, mainly driven by decreasing aluminum concentration and increased cations saturation in soil, due to liming and fertilization in long-term no-till cropping. Data revealed that long-term no-till cropping culminated in a decrease in Acidobacteria, Actinobacteria and Proteobacteria abundances. However, α- and β-Proteobacteria abundances were higher in the rhizosphere than in bulk soil, regardless of the time after forest-to-agriculture conversion. Changes in functional potential occurred predominantly in bulk soil, with decreases in functions related to potassium metabolism and virulence, disease and defense, while functions related to nucleic acids metabolism increased. Functions in the soybean rhizosphere remained stable, except for those related to potassium metabolism, which decreased after 20-year no-till cropping. Together, our results show that the soybean root system selects microbial taxa via trade-offs, to maintain functional resilience in the rhizosphere microbiome over time.
将原生林转化为农业是亚马逊土壤中微生物生物多样性丧失的主要原因。为了更好地了解这种影响，我们使用宏基因组学来研究大豆长期森林向农业转变过程中土壤和根际中的微生物模式和功能。长期的森林向农业转变导致了土壤和根际中微生物的同质化和多样性丧失，这主要是由于石灰和长期免耕种植中的施肥导致土壤中铝浓度降低和阳离子饱和度增加所致。数据显示，长期免耕种植导致 Acidobacteria、Actinobacteria 和 Proteobacteria 的丰度降低。然而，α-和β-Proteobacteria 的丰度在根际中高于土壤中，无论森林向农业转变后的时间如何。功能潜力的变化主要发生在土壤中，与钾代谢和毒力、疾病和防御相关的功能减少，而与核酸代谢相关的功能增加。大豆根际中的功能保持稳定，除了钾代谢相关的功能在 20 年免耕种植后减少。总之，我们的研究结果表明，大豆根系通过权衡选择微生物类群，以保持根际微生物组在时间上的功能弹性。
