Beier Sara, Rivers Adam R, Moran Mary Ann, Obernosterer Ingrid
1] CNRS, UMR 7621, Laboratoire d'Océanographie Microbienne, Banyuls/mer, France [2] Sorbonne Universités, UPMC Univ Paris 06, UMR 7621, Laboratoire d'Océanographie Microbienne, Observatoire Océanologique, Banyuls/mer, France.
US Department of Energy Joint Genome Institute, Walnut Creek, CA, USA.
ISME J. 2015 May;9(5):1141-51. doi: 10.1038/ismej.2014.206. Epub 2014 Nov 14.
Phenotypic plasticity (PP) is the development of alternate phenotypes of a given taxon as an adaptation to environmental conditions. Methodological limitations have restricted the quantification of PP to the measurement of a few traits in single organisms. We used metatranscriptomic libraries to overcome these challenges and estimate PP using the expressed genes of multiple heterotrophic organisms as a proxy for traits in a microbial community. The metatranscriptomes captured the expression response of natural marine bacterial communities grown on differing carbon resource regimes in continuous cultures. We found that taxa with different magnitudes of PP coexisted in the same cultures, and that members of the order Rhodobacterales had the highest levels of PP. In agreement with previous studies, our results suggest that continuous culturing may have specifically selected for taxa featuring a rather high range of PP. On average, PP and abundance changes within a taxon contributed equally to the organism's change in functional gene abundance, implying that both PP and abundance mediated observed differences in community function. However, not all functional changes due to PP were directly reflected in the bulk community functional response: gene expression changes in individual taxa due to PP were partly masked by counterbalanced expression of the same gene in other taxa. This observation demonstrates that PP had a stabilizing effect on a community's functional response to environmental change.
表型可塑性（PP）是指给定分类单元出现替代表型以适应环境条件的现象。方法学上的限制使得PP的量化仅限于对单个生物体少数性状的测量。我们利用宏转录组文库来克服这些挑战，并以多种异养生物的表达基因作为微生物群落中性状的替代指标来估计PP。宏转录组捕获了在连续培养中以不同碳源模式生长的天然海洋细菌群落的表达反应。我们发现，具有不同PP程度的分类单元共存于同一培养物中，红杆菌目成员的PP水平最高。与先前的研究一致，我们的结果表明，连续培养可能特别选择了具有较高PP范围的分类单元。平均而言，一个分类单元内的PP和丰度变化对该生物体功能基因丰度的变化贡献相同，这意味着PP和丰度都介导了观察到的群落功能差异。然而，并非所有由PP引起的功能变化都直接反映在整体群落功能反应中：由于PP导致的单个分类单元中的基因表达变化部分被其他分类单元中相同基因的平衡表达所掩盖。这一观察结果表明，PP对群落对环境变化的功能反应具有稳定作用。
