The origin of sex chromosomes has been hypothesized to involve the linkage of factors with antagonistic effects on male and female function. Garden asparagus (Asparagus officinalis L.) is an ideal species to test 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 (smFISH) 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, SOFF) 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 L.）是检验该假设的理想物种，因为X和Y染色体在细胞学上是同型的，并且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（smFISH）配对，直接暗示Y特异性基因，它们分别抑制雌性（雌蕊）发育，并且是雄性（花药）发育所必需的。比较相邻的X和Y染色体装配后，发现半合子性是抑制雌性器官发生的基因（女性功能的抑制子，SOFF）和促进男性功能（TAPETAL DEVELOPMENT AND 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的证据，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。