背景回顾：The Salicaceae, including Populus and Salix, are dioecious perennials that utilize different sex determination systems. This family provides a useful system to better understand the evolution of dioecy and sex chromosomes. 

主要研究：Here, a rare monoecious genotype of Salix purpurea L., 94003, was self- and cross-pollinated and progeny sex ratios were used to test hypotheses on possible mechanisms of sex determination. To delimit genomic regions associated with monoecious expression, the 94003 genome sequence was assembled and DNA- and RNA-Seq of progeny inflorescences was performed.

结果1：Based on alignments of progeny shotgun DNA sequences to the haplotype-resolved monoecious 94003 genome assembly and reference male and female genomes, a 1.15 Mb sex-linked region on Chr15W was confirmed to be absent in monecious plants. 

结果2：Inheritance of this structural variation is responsible for the loss of a male-suppressing function in what would otherwise be genetic females (ZW), resulting in monoecy (ZWH or WWH), or lethality, if homozygous (WHWH). 

结论：We present a refined, two-gene sex determination model for S. purpurea, mediated by ARR17 and GATA15 that is different from the single-gene ARR17 mediated system in the related genus Populus.

杨柳科包括杨属和柳属植物，是雌雄异株的多年生植物，采用不同的性别决定系统。该家族为深入研究雌雄异株和性染色体提供了一个十分有效的系统。本文中，作者通过对红皮柳一个十分罕见的雌雄同株基因型94003进行了自交和异交，通过计算子代的性别比例来测试可能的性别决定系统假设。为了鉴定与雌雄同株相关的基因组区域，作者对94003基因型进行了全基因组测序和组装，同时对其子代的花序进行了DNA和RNA测序。基于子代鸟枪法DNA测序比对到94003基因型单倍型基因组以及参考的雌、雄基因组，作者发现一段位于Chr15W上的1.15Mb的性别连锁区域在雌雄同株的植株中缺失。这一结构变异的遗传导致了雌株（ZW）中抑雄功能缺失，从而形成了雌雄异花同株，即基因型为ZWH或者WWH，当其为纯合子WHWH时致死。作者提出了一个由ARR17和GATA15双基因控制的红皮柳性别决定系统，这与杨属中所报道的单基因（ARR17）介导的性别决定系统有所不同。

** Lawrence B. Smart **