Institute of Bioinformatics, University of Georgia, Athens, USA.
DNA Res. 2011 Aug;18(4):253-61. doi: 10.1093/dnares/dsr014. Epub 2011 Jun 15.
Sarracenia species (pitcher plants) are carnivorous plants which obtain a portion of their nutrients from insects captured in the pitchers. To investigate these plants, we sequenced the transcriptome of two species, Sarracenia psittacina and Sarracenia purpurea, using Roche 454 pyrosequencing technology. We obtained 46 275 and 36 681 contigs by de novo assembly methods for S. psittacina and S. purpurea, respectively, and further identified 16 163 orthologous contigs between them. Estimation of synonymous substitution rates between orthologous and paralogous contigs indicates the events of genome duplication and speciation within the Sarracenia genus both occurred ∼2 million years ago. The ratios of synonymous and non-synonymous substitution rates indicated that 491 contigs have been under positive selection (K(a)/K(s) > 1). Significant proportions of these contigs were involved in functions related to binding activity. We also found that the greatest sequence similarity for both of these species was to Vitis vinifera, which is most consistent with a non-current classification of the order Ericales as an asterid. This study has provided new insights into pitcher plants and will contribute greatly to future research on this genus and its distinctive ecological adaptations.
猪笼草属（瓶子草属）是肉食性植物，它们从捕捉到的昆虫中获取部分营养。为了研究这些植物，我们使用 Roche 454 焦磷酸测序技术对两个物种，即猪笼草 psittacina 和猪笼草 purpurea 的转录组进行了测序。我们通过从头组装方法分别获得了 46275 个和 36681 个猪笼草 psittacina 和猪笼草 purpurea 的连续序列，进一步鉴定了它们之间的 16163 个直系同源连续序列。直系同源和旁系同源连续序列之间同义替换率的估计表明，猪笼草属的基因组复制和物种形成事件都发生在大约 200 万年前。同义替换率和非同义替换率的比值表明，有 491 个连续序列受到了正选择（K(a)/K(s) > 1）。这些连续序列的很大一部分参与了与结合活性相关的功能。我们还发现，这两个物种与葡萄的序列相似度最高，这与当前将真双子叶植物核心类群目（Ericales）归类为一个星状目最为一致。本研究为瓶子草属植物提供了新的见解，并将极大地促进对该属及其独特生态适应性的未来研究。
