Andreote Fernando Dini, Carneiro Raphael Tozelli, Salles Joana Falcão, Marcon Joelma, Labate Carlos Alberto, Azevedo João Lúcio, Araújo Welington Luiz
Departamento de Genética, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, P.O. Box 83, 13400-970, Piracicaba, Brazil.
Microb Ecol. 2009 Jan;57(1):82-93. doi: 10.1007/s00248-008-9405-8. Epub 2008 Jun 7.
The rhizosphere is an ecosystem exploited by a variety of organisms involved in plant health and environmental sustainability. Abiotic factors influence microorganism-plant interactions, but the microbial community is also affected by expression of heterologous genes from host plants. In the present work, we assessed the community shifts of Alphaproteobacteria phylogenetically related to the Rhizobiales order (Rhizobiales-like community) in rhizoplane and rhizosphere soils of wild-type and transgenic eucalyptus. A greenhouse experiment was performed and the bacterial communities associated with two wild-type (WT17 and WT18) and four transgenic (TR-9, TR-15, TR-22, and TR-23) eucalyptus plant lines were evaluated. The culture-independent approach consisted of the quantification, by real-time polymerase chain reaction (PCR), of a targeted subset of Alphaproteobacteria and the assessment of its diversity using PCR-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone libraries. Real-time quantification revealed a lesser density of the targeted community in TR-9 and TR-15 plants and diversity analysis by principal components analysis, based on PCR-DGGE, revealed differences between bacterial communities, not only between transgenic and nontransgenic plants, but also among wild-type plants. The comparison between clone libraries obtained from the transgenic plant TR-15 and wild-type WT17 revealed distinct bacterial communities associated with these plants. In addition, a culturable approach was used to quantify the Methylobacterium spp. in the samples where the identification of isolates, based on 16S rRNA gene sequences, showed similarities to the species Methylobacterium nodulans, Methylobacterium isbiliense, Methylobacterium variable, Methylobacterium fujisawaense, and Methylobacterium radiotolerans. Colonies classified into this genus were not isolated from the rhizosphere but brought in culture from rhizoplane samples, except for one line of the transgenic plants (TR-15). In general, the data suggested that, in most cases, shifts in bacterial communities due to cultivation of transgenic plants are similar to those observed when different wild-type cultivars are compared, although shifts directly correlated to transgenic plant cultivation may be found.
根际是一个被多种与植物健康和环境可持续性相关的生物体所利用的生态系统。非生物因素影响微生物与植物的相互作用，但微生物群落也受到宿主植物异源基因表达的影响。在本研究中，我们评估了野生型和转基因桉树根际和根际土壤中与根瘤菌目系统发育相关的α-变形菌纲群落（类根瘤菌目群落）的变化。进行了一项温室实验，评估了与两个野生型（WT17和WT18）和四个转基因（TR-9、TR-15、TR-22和TR-23）桉树品系相关的细菌群落。非培养方法包括通过实时聚合酶链反应（PCR）对α-变形菌纲的一个目标子集进行定量，并使用PCR-变性梯度凝胶电泳（DGGE）和16S rRNA基因克隆文库评估其多样性。实时定量显示TR-9和TR-15植物中目标群落的密度较低，基于PCR-DGGE的主成分分析的多样性分析揭示了细菌群落之间的差异，不仅在转基因植物和非转基因植物之间，而且在野生型植物之间。从转基因植物TR-15和野生型WT17获得的克隆文库之间的比较揭示了与这些植物相关的不同细菌群落。此外，采用可培养方法对甲基杆菌属进行定量，在基于16S rRNA基因序列鉴定分离株的样本中，显示与结节甲基杆菌、伊斯比利斯甲基杆菌、可变甲基杆菌、藤泽甲基杆菌和耐辐射甲基杆菌相似。除了一个转基因植物品系（TR-15）外，归类于该属的菌落不是从根际分离的，而是从根表样本培养而来的。总体而言，数据表明，在大多数情况下，由于转基因植物种植导致的细菌群落变化与比较不同野生型品种时观察到的变化相似，尽管可能会发现与转基因植物种植直接相关的变化。
