Taghavi Safiyh, Garafola Craig, Monchy Sébastien, Newman Lee, Hoffman Adam, Weyens Nele, Barac Tanja, Vangronsveld Jaco, van der Lelie Daniel
Brookhaven National Laboratory, Biology Department, Upton, NY 11973-5000, USA.
Appl Environ Microbiol. 2009 Feb;75(3):748-57. doi: 10.1128/AEM.02239-08. Epub 2008 Dec 5.
The association of endophytic bacteria with their plant hosts has a beneficial effect for many different plant species. Our goal is to identify endophytic bacteria that improve the biomass production and the carbon sequestration potential of poplar trees (Populus spp.) when grown in marginal soil and to gain an insight in the mechanisms underlying plant growth promotion. Members of the Gammaproteobacteria dominated a collection of 78 bacterial endophytes isolated from poplar and willow trees. As representatives for the dominant genera of endophytic gammaproteobacteria, we selected Enterobacter sp. strain 638, Stenotrophomonas maltophilia R551-3, Pseudomonas putida W619, and Serratia proteamaculans 568 for genome sequencing and analysis of their plant growth-promoting effects, including root development. Derivatives of these endophytes, labeled with gfp, were also used to study the colonization of their poplar hosts. In greenhouse studies, poplar cuttings (Populus deltoides x Populus nigra DN-34) inoculated with Enterobacter sp. strain 638 repeatedly showed the highest increase in biomass production compared to cuttings of noninoculated control plants. Sequence data combined with the analysis of their metabolic properties resulted in the identification of many putative mechanisms, including carbon source utilization, that help these endophytes to thrive within a plant environment and to potentially affect the growth and development of their plant hosts. Understanding the interactions between endophytic bacteria and their host plants should ultimately result in the design of strategies for improved poplar biomass production on marginal soils as a feedstock for biofuels.
内生细菌与其植物宿主的关联对许多不同植物物种都有有益影响。我们的目标是鉴定出在边际土壤中生长时能提高杨树（Populus spp.）生物量产量和碳固存潜力的内生细菌，并深入了解植物生长促进背后的机制。γ-变形菌纲的成员在从杨树和柳树中分离出的78种细菌内生菌中占主导地位。作为内生γ-变形菌纲优势属的代表，我们选择了肠杆菌属菌株638、嗜麦芽窄食单胞菌R551-3、恶臭假单胞菌W619和黏质沙雷氏菌568进行全基因组测序，并分析它们促进植物生长的作用，包括根系发育。这些内生菌的绿色荧光蛋白标记衍生物也用于研究它们在杨树宿主中的定殖情况。在温室研究中，与未接种对照植物的插条相比，接种肠杆菌属菌株638的杨树插条（Populus deltoides x Populus nigra DN-34）多次显示出最高的生物量产量增加。序列数据与它们代谢特性的分析相结合，鉴定出许多推定机制，包括碳源利用，这些机制有助于这些内生菌在植物环境中茁壮成长，并可能影响其植物宿主的生长和发育。了解内生细菌与其宿主植物之间的相互作用最终应能设计出提高边际土壤上杨树生物量产量的策略，以作为生物燃料的原料。
