背景回顾：Conifers dominate the world’s forest ecosystems and are the most widely planted tree species. 

提出问题：Their giant and complex genomes present great challenges for assembling a complete reference genome for evolutionary and genomic studies. 

结果1-基因组大小：We present a 25.4-Gb chromosome-level assembly of Chinese pine (Pinus tabuliformis) and revealed that its genome size is mostly attributable to huge intergenic regions and long introns with high transposable element (TE) content. 

结果2-基因长度与表达：Large genes with long introns exhibited higher expressions levels.

结果3-基因复制：Despite a lack of recent whole-genome duplication, 91.2% of genes were duplicated through dispersed duplication, and expanded gene families are mainly related to stress responses, which may underpin conifers’ adaptation, particularly in cold and/or arid conditions. 

结果4-生殖调控：The reproductive regulation network is distinct compared with angiosperms. 

结果5-TE移除：Slow removal of TEs with high-level methylation may have contributed to genomic expansion.

结论：This study provides insights into conifer evolution and resources for advancing research on conifer adaptation and development.

 摘 要 

针叶树种是世界森林生态系统的主要成员，是种植范围最广的树种。针叶树种的基因组庞大而复杂，难以组装出一个完整的参考基因组，这对于基因组演化和功能研究是一个挑战。本文中，作者组装了油松（Pinus tabuliformis）25.4 Gb的染色体水平基因组组装，揭示了其基因组大小主要归因于基因间区较大、且内含子较长，含有较多的转座因子（TE）。有趣的是，内含子较长的基因反而表现出较高的表达水平。另外，尽管油松基因组上未检测到近期的全基因组复制，但91.2%的基因是通过散布复制进行复制的，并且扩张的基因家族主要与胁迫响应有关，这可能与针叶树适应其生存环境、尤其是寒冷和/或干旱条件有关。与被子植物相比，裸子植物的生殖调控网络明显存在差异。油松基因组中，具有高水平甲基化的TEs去除较为缓慢，这可能促进了针叶树种基因组的扩展。本文的研究为针叶树种的演化提供了新的视野，同时也为推进针叶树适应性和发育研究提供了基因组资源。

 通讯作者 

** Harry X. Wu **