Department of Biology, Case Western Reserve University, Cleveland, OH 44106, USA
University of California, Davis, CA, USA.
AoB Plants. 2015 Mar 27;7:plv030. doi: 10.1093/aobpla/plv030.
Soil ecologists have debated the relative importance of dispersal limitation and ecological factors in determining the structure of soil microbial communities. Recent evidence suggests that 'everything is not everywhere', and that microbial communities are influenced by both dispersal limitation and ecological factors. However, we still do not understand the relative explanatory power of spatial and ecological factors, including plant species identity and even plant relatedness, for different fractions of the soil microbial community (i.e. bacterial and fungal communities). To ask whether factors such as plant species, soil chemistry, spatial location and plant relatedness influence rhizosphere community composition, we examined field-collected rhizosphere soil of seven congener pairs that occur at Bodega Bay Marine Reserve, CA, USA. We characterized differences in bacterial and fungal communities using terminal-restriction fragment length polymorphism. Plant species identity was the single best statistical predictor of both bacterial and fungal community composition in the root zone. Soil microbial community structure was also correlated with soil chemistry. The third best predictor of bacterial and fungal communities was spatial location, confirming that everything is not everywhere. Variation in microbial community composition was also related to combinations of spatial location, soil chemistry and plant relatedness, suggesting that these factors do not act independently. Plant relatedness explained less of the variation than plant species, soil chemistry, or spatial location. Despite some congeners occupying different habitats and being spatially distant, rhizosphere fungal communities of plant congeners were more similar than expected by chance. Bacterial communities from the same samples were only weakly similar between plant congeners. Thus, plant relatedness might influence soil fungal, more than soil bacterial, community composition.
土壤生态学家一直在争论扩散限制和生态因素在决定土壤微生物群落结构中的相对重要性。最近的证据表明，“并非一切皆无处不在”，微生物群落既受到扩散限制的影响，也受到生态因素的影响。然而，我们仍然不了解空间和生态因素（包括植物物种身份甚至植物亲缘关系）对土壤微生物群落不同部分（即细菌和真菌群落）的相对解释力。为了研究植物物种、土壤化学、空间位置和植物亲缘关系等因素是否影响根际群落组成，我们研究了美国加利福尼亚州博德加湾海洋保护区采集的七个同属种对的根际土壤。我们使用末端限制性片段长度多态性来描述细菌和真菌群落的差异。植物物种身份是根区细菌和真菌群落组成的最佳单一统计预测因子。土壤微生物群落结构也与土壤化学相关。细菌和真菌群落的第三大最佳预测因子是空间位置，这证实了并非一切皆无处不在。微生物群落组成的变化也与空间位置、土壤化学和植物亲缘关系的组合有关，表明这些因素并非独立作用。与植物物种、土壤化学或空间位置相比，植物亲缘关系解释的变异较少。尽管一些同属种占据不同的栖息地并且空间距离较远，但同属种的根际真菌群落比随机预期的更相似。来自同一样本的细菌群落之间仅存在微弱的相似性。因此，植物亲缘关系可能影响土壤真菌群落的组成，而不是土壤细菌群落的组成。
