Given the 2,400-fold range of genome sizes (0.06–148.9 Gbp (gigabase pair)) of seed plants (angiosperms and gymnosperms) with a broadly similar gene content (amounting to approximately 0.03 Gbp), the repeat-sequence content of the genome might be expected to increase with genome size, resulting in the largest genomes consisting almost entirely of repetitive sequences. Here we test this prediction, using the same bioinformatic approach for 101 species to ensure consistency in what constitutes a repeat. We reveal a fundamental change in repeat turnover in genomes above around 10 Gbp, such that species with the largest genomes are only about 55% repetitive. Given that genome size influences many plant traits, habits and life strategies, this fundamental shift in repeat dynamics is likely to affect the evolutionary trajectory of species lineages.

鉴于具有广泛相似基因含量（约 0.03 Gbp）的种子植物（被子植物和裸子植物）的基因组大小范围为 2,400 倍（0.06-148.9 Gbp（千兆碱基对）），基因组的重复序列含量可能预计会随着基因组大小而增加，从而导致最大的基因组几乎完全由重复序列组成。在这里，我们测试了这一预测，对 101 个物种使用相同的生物信息学方法，以确保构成重复的内容的一致性。我们揭示了高于 10 Gbp 的基因组重复周转的根本变化，因此具有最大基因组的物种只有大约 55% 的重复。鉴于基因组大小影响许多植物性状、习性和生活策略，重复动态的这种根本转变可能会影响物种谱系的进化轨迹。