Key message

Cosexual Populus ×canescens plants are inconstant females with life course plasticity of sex phenotype and can reproduce by selfing.

Abstract

Populus species are dioecious, but deviations from dioecy are reported in some cases. The objectives of this study were to investigate the phenotypic expression and the inheritance of subdioecy in a Populus ×canescens pedigree. The F₁ progeny was monitored for sex during 14 years. Thirty per cent of individuals expressed deviations from dioecy and long-term plasticity of sex. Some plants started flowering as male, then became cosexual, and finally turned female. Two cosexual individuals were self-pollinated and generated a selfed progeny markedly impaired by inbreeding depression, but able to reproduce by outcrossing. Sex segregation of the F₁ progeny statistically fitted the expected ratio 1:2:1 (female:male:cosexual). By analysis of DNA markers, the cosexual individuals were genetically clustered with the females. The segregation ratio and the genetic profile indicated that cosexual plants were female with altered sex phenotype. Linkage analysis identified a putative sex-determining region with suppressed recombination on chromosome 19 of the male Populus tremula parent. The male sex trait was linked to the pericentromeric region of the P. tremula chromosome 19, whereas the cosexual trait was linked to chromosome 19 of the female Populus alba parent. A genetic model is proposed to explain inheritance and phenotypic expression of sex.

中文翻译：

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对亚种次生胡杨（Populus×canescens）家庭的长期研究揭示了雌性的性不稳定性和两性植物的繁殖行为。

关键信息

雌性胡杨 × canescens植物是雌性不定的雌性，其生命表型具有可塑性，并且可以通过自交繁殖。

抽象

杨属雌雄异株，但在某些情况下据报道与雌雄异株背离。这项研究的目的是调查表型表达和subdioecy的在继承杨 ×藜血统。在14年中监测了F ₁后代的性别。30％的人表示不适应雌雄异体和长期的可塑性。一些植物开始以雄花的形式开花，然后成为两性，最后变成雌花。两个性交个体是自花授粉的，并产生了近亲抑郁明显受损的自交后代，但能够通过异交繁殖。F _1的性别隔离后代统计学上符合预期的比例1：2：1（女性：男性：同性恋）。通过分析DNA标记，将两性个体与雌性遗传聚类。分离比和遗传特征表明，两性植物是雌性，具有改变的性别表型。连锁分析确定了一个推测的性别决定区域，该区域在雄性杨杨亲本的19号染色体上具有抑制的重组。男性性状与银杏假单胞菌第19号染色体的着丝粒区有关，而同性恋的性状与雌性杨白杨亲本的19号染色体有关。提出了遗传模型来解释性的遗传和表型表达。