Narrowing the genomic regions responsible for sex determination in spinach

众所周知，菠菜是雌雄异株。然而，雌雄同株植物也可以出现在这个物种中。在雌雄异株的菠菜植株中，性别表达是由一对被称为X和Y的基因控制的。我们之前的研究表明，一个控制雌雄同株的不完全显性基因与X/Y有关。本研究开发的4个y连锁AFLP标记转化为序列特征扩增区（SCAR）标记。使用4个SCAR标记和3个已知的Y连锁标记进行连锁分析表明，男性决定基因(Y)周围的重组受到抑制。用y连锁标记分离的菠菜基因组BAC克隆分析表明，雄性特异性（非重组）区域至少大于840 kbp。此外，发现该染色体区域的大部分由散布的重复元件（如反转录子）负责，而在该区域仅鉴定出少数蛋白质编码基因。

Spinach is widely known to be dioecious. However, monoecious plants can also occur in this species. Sex expression in dioecious spinach plants is controlled by a single gene pair termed X and Y. Our previous study showed that a single, incompletely dominant gene, which controls the monoecious condition, is linked to X/Y.The four Y-linked AFLP markers developed in this study were converted into sequence-characterized amplified region (SCAR) markers. Linkage analysis using the four SCAR markers and three already-known Y-linked markers suggested that recombination is suppressed around the male-determining gene (Y). Analysis of spinach genomic BAC clones isolated with the Y-linked markers suggested that the male-specific (non-recombining) region is at least larger than 840 kbp. Further, most part of this chromosomal region was found to be accounted for by interspersed repeated elements, e.g. retroposons, while only a few protein-coding genes were identified in this region.