Lambais M R, Barrera S E, Santos E C, Crowley D E, Jumpponen A
Departamento de Ciência do Solo, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, 13418-900, Brazil.
Department of Environmental Sciences, University of California, 900 University Ave, Riverside, CA, 92521, USA.
Microb Ecol. 2017 Jan;73(1):123-134. doi: 10.1007/s00248-016-0878-6. Epub 2016 Nov 16.
The phyllosphere of the Brazilian Atlantic Forest has been estimated to contain several million bacterial species that are associated with approximately 20000 plant species. Despite the high bacterial diversity in the phyllosphere, the function of these microorganisms and the mechanisms driving their community assembly are largely unknown. In this study, we characterized the bacterial communities in the phyllospheres of four tree species of the Atlantic Forest (Mollinedia schottiana, Ocotea dispersa, Ocotea teleiandra, and Tabebuia serratifolia) and their metaproteomes to examine the basic protein functional groups expressed in the phyllosphere. Bacterial community analyses using 16S rRNA gene sequencing confirmed prior observations that plant species harbor distinct bacterial communities and that plants of the same taxon have more similar communities than more distantly related taxa. Using LC-ESI-Q-TOF, we identified 216 nonredundant proteins, based on 3503 peptide mass spectra. Most protein families were shared among the phyllosphere communities, suggesting functional redundancy despite differences in the species compositions of the bacterial communities. Proteins involved in glycolysis and anaerobic carbohydrate metabolism, solute transport, protein metabolism, cell motility, stress and antioxidant responses, nitrogen metabolism, and iron homeostasis were among the most frequently detected. In contrast to prior studies on crop plants and Arabidopsis, a low abundance of OTUs related to Methylobacterium and no proteins associated with the metabolism of one-carbon molecules were detected in the phyllospheres of the tree species studied here. Our data suggest that even though the phyllosphere bacterial communities of different tree species are phylogenetically diverse, their metaproteomes are functionally convergent with respect to traits required for survival on leaf surfaces.
据估计，巴西大西洋森林的叶际含有数百万种细菌，这些细菌与约20000种植物相关。尽管叶际细菌多样性很高，但这些微生物的功能以及驱动其群落组装的机制在很大程度上仍不清楚。在本研究中，我们对大西洋森林中四种树种（肖氏南美杨桐、散生桂、远距桂和锯齿风铃木）的叶际细菌群落及其元蛋白质组进行了表征，以研究叶际中表达的基本蛋白质功能组。使用16S rRNA基因测序进行的细菌群落分析证实了先前的观察结果，即植物物种拥有不同的细菌群落，并且同一分类群的植物比亲缘关系较远的分类群具有更相似的群落。使用液相色谱-电喷雾-四极杆-飞行时间质谱仪，我们基于3503个肽质量谱鉴定了216种非冗余蛋白质。大多数蛋白质家族在叶际群落中共享，这表明尽管细菌群落的物种组成不同，但存在功能冗余。参与糖酵解和厌氧碳水化合物代谢、溶质转运、蛋白质代谢、细胞运动、应激和抗氧化反应、氮代谢以及铁稳态的蛋白质是最常检测到的。与先前对农作物和拟南芥的研究不同，在此研究的树种叶际中未检测到与甲基杆菌相关的低丰度操作分类单元，也未检测到与一碳分子代谢相关的蛋白质。我们的数据表明，尽管不同树种的叶际细菌群落在系统发育上具有多样性，但它们的元蛋白质组在叶表面生存所需的性状方面功能趋同。
