Distinct Microbial Communities within the Endosphere and Rhizosphere of Populus deltoides Roots across Contrasting Soil Types
Distinct Microbial Communities within the Endosphere and Rhizosphere of Populus deltoides Roots across Contrasting Soil Types
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DOI：
10.1128/aem.05255-11
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发表时间：
2011-09-01
影响因子：
4.4
通讯作者：
Schadt, Christopher W.
中科院分区：
文献类型：
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作者：
Gottel, Neil R.;Castro, Hector F.;Schadt, Christopher W.
杨树根际界面是细菌、真菌与寄主植物之间多种关系的联结点，是研究植物与微生物相互作用的理想模型。然而，这种研究一般仅限于温室和种植系统。在这里，我们分析了微生物群落从根内生和根际生境的美洲黑杨在成熟的天然树木从高地和洼地在田纳西州中部的网站。群落分析利用454焦磷酸测序，其中单独的引物靶向细菌16S rRNA的V4区域和真菌28S rRNA基因的D1/D2区域。根际细菌以酸杆菌（31%）和α-变形菌（30%）为主，而大多数内生菌来自γ-变形菌（54%）和α-变形菌（23%）。单个类假单胞菌操作分类单位（OTU）占内生细菌序列的34%。内生细菌丰富度也是高度可变的，10倍低于根际样品来自相同的根。真菌根际和内生菌样品具有大致相等量的盘菌亚门（40%），而伞菌亚门在根际（34%）比根际（17%）更丰富。真菌和细菌根际样品高度聚类相比，更可变的内生菌样品在UniFrac主坐标分析，无论高地或低地网站的起源。OTU相对丰度模式的层次聚类也表明，最丰富的细菌和真菌OTU倾向于在内生菌或根际样品中占主导地位，但不是两者兼而有之。总之，这些研究结果表明，根内生菌群落是不同的组合，而不是机会的根际子集。
The root-rhizosphere interface of Populus is the nexus of a variety of associations between bacteria, fungi, and the host plant and an ideal model for studying interactions between plants and microorganisms. However, such studies have generally been confined to greenhouse and plantation systems. Here we analyze microbial communities from the root endophytic and rhizospheric habitats of Populus deltoides in mature natural trees from both upland and bottomland sites in central Tennessee. Community profiling utilized 454 pyrosequencing with separate primers targeting the V4 region for bacterial 16S rRNA and the D1/D2 region for fungal 28S rRNA genes. Rhizosphere bacteria were dominated by Acidobacteria (31%) and Alphaproteobacteria (30%), whereas most endophytes were from the Gammaproteobacteria (54%) as well as Alphaproteobacteria (23%). A single Pseudomonas-like operational taxonomic unit (OTU) accounted for 34% of endophytic bacterial sequences. Endophytic bacterial richness was also highly variable and 10-fold lower than in rhizosphere samples originating from the same roots. Fungal rhizosphere and endophyte samples had approximately equal amounts of the Pezizomycotina (40%), while the Agaricomycotina were more abundant in the rhizosphere (34%) than endosphere (17%). Both fungal and bacterial rhizosphere samples were highly clustered compared to the more variable endophyte samples in a UniFrac principal coordinates analysis, regardless of upland or bottomland site origin. Hierarchical clustering of OTU relative abundance patterns also showed that the most abundant bacterial and fungal OTUs tended to be dominant in either the endophyte or rhizosphere samples but not both. Together, these findings demonstrate that root endophytic communities are distinct assemblages rather than opportunistic subsets of the rhizosphere.