Carey Sarah B, Aközbek Laramie, Lovell John T, Jenkins Jerry, Healey Adam L, Shu Shengqiang, Grabowski Paul, Yocca Alan, Stewart Ada, Jones Teresa, Barry Kerrie, Rajasekar Shanmugam, Talag Jayson, Scutt Charlie, Lowry Porter P, Munzinger Jérôme, Knox Eric B, Soltis Douglas E, Soltis Pamela S, Grimwood Jane, Schmutz Jeremy, Leebens-Mack James, Harkess Alex
HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA.
Department of Crop, Soil, and Environmental Sciences, Auburn University, Auburn, AL, USA.
Nat Plants. 2024 Dec;10(12):1944-1954. doi: 10.1038/s41477-024-01858-x. Epub 2024 Nov 25.
Sex chromosomes have evolved hundreds of times across the flowering plant tree of life; their recent origins in some members of this clade can shed light on the early consequences of suppressed recombination, a crucial step in sex chromosome evolution. Amborella trichopoda, the sole species of a lineage that is sister to all other extant flowering plants, is dioecious with a young ZW sex determination system. Here we present a haplotype-resolved genome assembly, including highly contiguous assemblies of the Z and W chromosomes. We identify a ~3-megabase sex-determination region (SDR) captured in two strata that includes a ~300-kilobase inversion that is enriched with repetitive sequences and contains a homologue of the Arabidopsis METHYLTHIOADENOSINE NUCLEOSIDASE (MTN1-2) genes, which are known to be involved in fertility. However, the remainder of the SDR does not show patterns typically found in non-recombining SDRs, such as repeat accumulation and gene loss. These findings are consistent with the hypothesis that dioecy is derived in Amborella and the sex chromosome pair has not significantly degenerated.
在开花植物的生命之树上，性染色体已经进化了数百次；它们在该进化枝某些成员中的近期起源，能够揭示重组抑制的早期后果，而重组抑制是性染色体进化中的关键一步。无油樟是所有其他现存开花植物的姐妹谱系中的唯一物种，它是雌雄异株的，具有一个年轻的ZW性别决定系统。在此，我们展示了一个单倍型解析的基因组组装，包括Z染色体和W染色体的高度连续组装。我们确定了一个约3兆碱基的性别决定区域（SDR），该区域分布在两个层次中，其中包括一个约300千碱基的倒位，该倒位富含重复序列，并包含拟南芥甲硫腺苷核苷酶（MTN1-2）基因的一个同源物，已知该基因与育性有关。然而，SDR的其余部分并未表现出非重组SDR中常见的模式，如重复序列积累和基因丢失。这些发现与无油樟中雌雄异株是衍生而来的这一假设一致，并且性染色体对尚未显著退化。
