Acquisti Claudia, Elser James J, Kumar Sudhir
Mol Biol Evol. 2009 May;26(5):953-6. doi: 10.1093/molbev/msp038. Epub 2009 Mar 2.
Phenotypes and behaviors respond to resource constraints via adaptation, but the influence of ecological limitations on the composition of eukaryotic genomes is still unclear. We trace connections between plant ecology and genomes through their elemental composition. Inorganic sources of nitrogen (N) are severely limiting to plants in natural ecosystems. This constraint would favor the use of N-poor nucleotides in plant genomes. We show that the transcribed segments of undomesticated plant genomes are the most N poor, with genomes and proteomes bearing signatures of N limitation. Consistent with the predictions of natural selection for N conservation, the precursors of transcriptome show the greatest deviations from Chargaff's second parity rule. Furthermore, crops show higher N contents than undomesticated plants, likely due to the relaxation of natural selection owing to the use of N-rich fertilizers. These findings indicate a fundamental role of N limitation in the evolution of plant genomes, and they link the genomes with the ecosystem context within which biota evolve.
表型和行为通过适应对资源限制做出反应，但生态限制对真核生物基因组组成的影响仍不明确。我们通过植物的元素组成来追溯植物生态学与基因组之间的联系。在自然生态系统中，无机氮源对植物来说是严重受限的。这种限制有利于植物基因组中使用含氮量低的核苷酸。我们发现，未驯化植物基因组的转录片段含氮量最低，基因组和蛋白质组都带有氮限制的特征。与自然选择对氮保存的预测一致，转录组的前体与查加夫第二对等规则的偏差最大。此外，作物的含氮量高于未驯化植物，这可能是由于使用富含氮的肥料导致自然选择放松所致。这些发现表明氮限制在植物基因组进化中具有重要作用，并且将基因组与生物群落进化所处的生态系统背景联系起来。
