Beijing Key Laboratory of Greening Plants Breeding, Beijing Academy of Forestry and Landscape Architecture, Beijing 100102, China.
Beijing Key Laboratory of Development and Quality Control of Ornamental Crops, Department of Ornamental Horticulture, China Agricultural University, Beijing 100193, China; Sanya Institute of China Agricultural University, Sanya 572024, China.
Int J Biol Macromol. 2023 Dec 31;253(Pt 5):127132. doi: 10.1016/j.ijbiomac.2023.127132. Epub 2023 Sep 29.
White ash (Fraxinus americana linn.) originates from the southeastern United States. It is a tall and fast-growing tree species with strong salt-alkali resistance and cold tolerance, making it an important reforestation species and widely planted worldwide. Here, we completed the chromosome-level reference genome assembly of F. americana based on Illumina, PacBio, and Hi-C reads, with a genome size of 878.98 Mb, an N50 of 3.27 Mb, and a heterozygosity rate of 0.3 %. Based on de novo prediction, transcriptome prediction, and homology-based protein prediction, we obtained 39,538 genes. Approximately 843.21 Mb of the assembly genome was composed of 37,928 annotated protein-coding genes, with a gene function annotation rate of 95.93 %. 99.94 % of the overlap clusters (877.44 Mb) were anchored to 23 chromosomes. Synteny analysis of F. americana and other Oleaceae plants showed that F. americana underwent frequent chromosome rearrangements. The amplification of the Ale transposons effectively promoted the genome size of F. americana. Compared with other Oleaceae plants, the Glutathione S-transferase (GST) gene family in the F. americana genome has undergone significant expansion, which may help F. americana cope with adverse natural environments. Furthermore, we found that key enzyme-coding gene families related to lignin biosynthesis were expanded and highly expressed in F. americana leaves. These key genes drive lignin synthesis and benefit F. americana in fast-growing, as well as resisting biotic and abiotic stress. Overall, the F. americana genome assembly provides insights into the evolution of Oleaceae plants and provides abundant resources for breeding and germplasm conservation of white ash.
白蜡树（Fraxinus americana Linn.）原产于美国东南部。它是一种高大且生长迅速的树种，具有较强的耐盐碱性和耐寒性，是一种重要的造林树种，在全球范围内广泛种植。在这里，我们基于 Illumina、PacBio 和 Hi-C 读取完成了 F. americana 的染色体水平参考基因组组装，基因组大小为 878.98 Mb，N50 为 3.27 Mb，杂合率为 0.3%。基于从头预测、转录组预测和基于同源性的蛋白质预测，我们获得了 39538 个基因。大约 843.21 Mb 的组装基因组由 37928 个注释蛋白编码基因组成，基因功能注释率为 95.93%。99.94%的重叠群（877.44 Mb）被锚定到 23 条染色体上。F. americana 和其他木犀科植物的共线性分析表明，F. americana 经历了频繁的染色体重排。Ale 转座子的扩增有效地促进了 F. americana 基因组的大小。与其他木犀科植物相比，F. americana 基因组中的谷胱甘肽 S-转移酶（GST）基因家族发生了显著扩张，这可能有助于 F. americana 应对不利的自然环境。此外，我们发现与木质素生物合成相关的关键酶编码基因家族在 F. americana 叶片中发生了扩张并高度表达。这些关键基因驱动木质素的合成，使 F. americana 能够快速生长，并抵抗生物和非生物胁迫。总的来说，F. americana 基因组组装为木犀科植物的进化提供了深入的了解，并为白蜡树的选育和种质资源保护提供了丰富的资源。
