Institute of Applied Microbiology (IFZ), Justus Liebig University Giessen, D-35392 Giessen, Germany.
Biomedical Research Center Seltersberg - Imaging Unit, Justus Liebig University Giessen, D-35392 Giessen, Germany.
FEMS Microbiol Ecol. 2020 Aug 1;96(8). doi: 10.1093/femsec/fiaa087.
The leaf-colonizing bacterial microbiota was studied in a long-term warming experiment on a permanent grassland, which had been continuously exposed to increased surface temperature (+2°C) for more than six years. Two abundant plant species, Arrhenatherum elatius and Galium album, were studied. Surface warming reduced stomata opening and changed leaf metabolite profiles. Leaf surface colonization and the concentration of leaf-associated bacterial cells were not affected. However, bacterial 16S ribosomal RNA (rRNA) gene amplicon Illumina sequencing showed significant temperature effects on the plant species-specific phyllosphere microbiota. Warming partially affected the concentrations of cultured bacteria and had a significant effect on the composition of most abundant cultured plant species-specific bacteria. The abundance of Sphingomonas was significantly reduced. Sphingomonas isolates from warmed plots represented different phylotypes, had different physiological traits and were better adapted to higher temperatures. Among Methylobacterium isolates, a novel phylotype with a specific mxaFtype was cultured from plants of warmed plots while the most abundant phylotype cultured from control plots was strongly reduced. This study clearly showed a correlation of long-term surface warming with changes in the plant physiology and the development of a physiologically and genetically adapted phyllosphere microbiota.
本研究对长期增温实验中的叶际细菌微生物群进行了研究，该实验在一个永久性草原上进行，已经连续六年持续暴露于地表增温（+2°C）。本研究以两种丰富的植物物种，赖草（Arrhenatherum elatius）和拉拉藤（Galium album）为研究对象。地表增温减少了气孔开度并改变了叶片代谢物图谱。然而，叶表定殖和叶相关细菌细胞的浓度并未受到影响。然而，细菌 16S 核糖体 RNA（rRNA）基因扩增子 Illumina 测序显示，温度对物种特异性叶际微生物群有显著影响。增温部分影响了可培养细菌的浓度，并且对大多数丰富的植物物种特异性细菌的组成有显著影响。鞘氨醇单胞菌的丰度显著降低。来自增温样地的鞘氨醇单胞菌分离株代表不同的系统发育型，具有不同的生理特征，并且对较高温度的适应性更强。在甲基杆菌属分离株中，从增温样地的植物中培养出一种具有特定 mxaF 型的新型系统发育型，而从对照样地中培养出的最丰富的系统发育型则显著减少。本研究清楚地表明，长期的地表增温与植物生理学变化以及生理和遗传上适应叶际微生物群的发展之间存在相关性。
