Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
Gigascience. 2022 Dec 28;12. doi: 10.1093/gigascience/giad005. Epub 2023 Feb 21.
Musa beccarii (Musaceae) is a banana species native to Borneo, sometimes grown as an ornamental plant. The basic chromosome number of Musa species is x = 7, 10, or 11; however, M. beccarii has a basic chromosome number of x = 9 (2n = 2x = 18), which is the same basic chromosome number of species in the sister genera Ensete and Musella. Musa beccarii is in the section Callimusa, which is sister to the section Musa. We generated a high-quality chromosome-scale genome assembly of M. beccarii to better understand the evolution and diversity of genomes within the family Musaceae.
The M. beccarii genome was assembled by long-read and Hi-C sequencing, and genes were annotated using both long Iso-seq and short RNA-seq reads. The size of M. beccarii was the largest among all known Musaceae assemblies (∼570 Mbp) due to the expansion of transposable elements and increased 45S ribosomal DNA sites. By synteny analysis, we detected extensive genome-wide chromosome fusions and fissions between M. beccarii and the other Musa and Ensete species, far beyond those expected from differences in chromosome number. Within Musaceae, M. beccarii showed a reduced number of terpenoid synthase genes, which are related to chemical defense, and enrichment in lipid metabolism genes linked to the physical defense of the cell wall. Furthermore, type III polyketide synthase was the most abundant biosynthetic gene cluster (BGC) in M. beccarii. BGCs were not conserved in Musaceae genomes.
The genome assembly of M. beccarii is the first chromosome-scale genome assembly in the Callimusa section in Musa, which provides an important genetic resource that aids our understanding of the evolution of Musaceae genomes and enhances our knowledge of the pangenome.
贝多氏蕉（Musaceae）是一种原产于婆罗洲的香蕉物种，有时作为观赏植物种植。大多数蕉属植物的基本染色体数目为 x = 7、10 或 11；然而，贝多氏蕉的基本染色体数目为 x = 9（2n = 2x = 18），与姐妹属恩塞特属和野蕉属的基本染色体数目相同。贝多氏蕉属于 Callimusa 组，与 Musa 组为姐妹群。我们生成了贝多氏蕉的高质量染色体水平基因组组装，以更好地理解 Musaceae 家族内基因组的进化和多样性。
通过长读长和 Hi-C 测序组装了贝多氏蕉的基因组，并使用长 Iso-seq 和短 RNA-seq reads 注释基因。由于转座元件的扩张和 45S 核糖体 DNA 位点的增加，贝多氏蕉的基因组大小是所有已知的 Musaceae 组装中最大的（约 570 Mbp）。通过共线性分析，我们检测到贝多氏蕉与其他蕉属和恩塞特属物种之间广泛的全基因组染色体融合和断裂，远远超出了染色体数目的差异所预期的范围。在 Musaceae 中，贝多氏蕉显示萜烯合酶基因数量减少，这些基因与化学防御有关，而与细胞壁物理防御相关的脂质代谢基因富集。此外，III 型聚酮合酶是贝多氏蕉中最丰富的生物合成基因簇（BGC）。BGC 在 Musaceae 基因组中没有保守。
贝多氏蕉的基因组组装是 Musa 中 Callimusa 组的第一个染色体水平基因组组装，为我们理解 Musaceae 基因组的进化提供了重要的遗传资源，并增强了我们对泛基因组的认识。
