The origin and early evolution of sex chromosomes have been hypothesized to involve the linkage of factors with antagonistic effects on male and female function. Garden asparagus (Asparagus officinalis) is an ideal species to investigate this hypothesis, as the X and Y chromosomes are cytologically homomorphic and evolved from an ancestral autosome pair in association with a shift from hermaphroditism to dioecy. Mutagenesis screens paired with single-molecule fluorescence in situ hybridization directly implicate Y-specific genes that respectively suppress female (pistil) development and are necessary for male (anther) development. Comparison of contiguous X and Y chromosome assemblies shows that hemizygosity underlies the loss of recombination between the genes suppressing female organogenesis (SUPPRESSOR OF FEMALE FUNCTION) and promoting male function (TAPETAL DEVELOPMENT AND FUNCTION1 [aspTDF1]). We also experimentally demonstrate the function of aspTDF1. These findings provide direct evidence that sex chromosomes can function through linkage of two sex determination genes.

假设性染色体的起源和早期进化涉及对男性和女性功能具有拮抗作用的因素的联系。芦笋（Asparagus officinalis）是研究此假设的理想物种，因为X和Y染色体在细胞学上是同态的，并从祖先常染色体对进化而来，从雌雄同体转变为对雌性。诱变筛选与单分子荧光原位杂交配对，直接暗示分别抑制雌性（雌蕊）发育且是雄性（花药）发育所必需的Y特异性基因。比较连续的X和Y染色体装配显示，半合子性是抑制女性器官发生的基因之间重组损失的基础（女功能抑制物）和促进男性功能（绒毡层发展与FUNCTION1 [ aspTDF1 ]）。我们还通过实验证明了aspTDF1的功能。这些发现提供了直接证据，表明性染色体可以通过两个性别决定基因的连锁而起作用。