Bei Qicheng, Moser Gerald, Müller Christoph, Liesack Werner
Research Group Methanotrophic Bacteria, and Environmental Genomics/Transcriptomics Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 10, 35043 Marburg, Germany.
Department of Plant Ecology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany.
Sci Total Environ. 2021 Aug 25;784:147036. doi: 10.1016/j.scitotenv.2021.147036. Epub 2021 Apr 20.
Knowledge on how grassland microbiota responds on gene expression level to winter-summer change of seasons is poor. Here, we used a combination of quantitative PCR-based assays and metatranscriptomics to assess the impact of seasonality on the rhizospheric microbiota in temperate European grassland. Bacteria dominated, being at least one order of magnitude more abundant than fungi. Despite a fivefold summer increase in bacterial community size, season had nearly no effect on microbiome diversity. It, however, had a marked impact on taxon-specific gene expression, with 668 genes significantly differing in relative transcript abundance between winter and summer samples. Acidobacteria, Bacteroidetes, Planctomycetes, and Proteobacteria showed a greater relative gene expression activity in winter, while mRNA of Actinobacteria and Fungi was, relative to other taxa, significantly enriched in summer. On functional level, mRNA involved in protein turnover (e.g., transcription and translation) and cell maintenance (e.g., chaperones that protect against cell freezing damage such as GroEL and Hsp20) were highly enriched in winter. By contrast, mRNA involved in central carbon and amino acid metabolisms had a greater abundance in summer. Among carbohydrate-active enzymes, transcripts of GH36 family (hemicellulases) were highly enriched in winter, while those encoding GH3 family (cellulases) showed increased abundance in summer. The seasonal differences in plant polymer breakdown were linked to a significantly greater microbial network complexity in winter than in summer. Conceptually, the winter-summer change in microbiome functioning can be well explained by a shift from stress-tolerator to high-yield life history strategy.
关于草原微生物群如何在基因表达水平上响应季节冬夏变化的了解还很少。在这里，我们结合基于定量PCR的分析方法和宏转录组学来评估季节性对欧洲温带草原根际微生物群的影响。细菌占主导地位，其丰度至少比真菌高一个数量级。尽管夏季细菌群落规模增加了五倍，但季节对微生物组多样性几乎没有影响。然而，它对特定分类群的基因表达有显著影响，冬夏样本之间有668个基因的相对转录丰度存在显著差异。酸杆菌门、拟杆菌门、浮霉菌门和变形菌门在冬季表现出更高的相对基因表达活性，而放线菌门和真菌的mRNA相对于其他分类群在夏季显著富集。在功能水平上，参与蛋白质周转（如转录和翻译）和细胞维持（如防止细胞冷冻损伤的伴侣蛋白，如GroEL和Hsp20）的mRNA在冬季高度富集。相比之下，参与中心碳和氨基酸代谢的mRNA在夏季丰度更高。在碳水化合物活性酶中，GH36家族（半纤维素酶）的转录本在冬季高度富集，而编码GH3家族（纤维素酶）的转录本在夏季丰度增加。植物聚合物分解的季节性差异与冬季微生物网络复杂性显著高于夏季有关。从概念上讲，微生物组功能的冬夏变化可以通过从耐胁迫到高产生活史策略的转变得到很好的解释。
