The Structure and Function of Sex Chromosomes in Plants

稳定的性别决定遗传机制是维持物种中不同性别的先决条件。这反过来要求那些促进或抑制女性和男性表达的基因位于同一染色体上。染色体性别决定在植物中很少见，但在动物中广泛存在，而且几乎总是伴随着X和Y染色体的形态分化。植物中性染色体的起源相对较近，这意味着在许多情况下，也存在缺乏性染色体的密切相关物种。在亲缘关系密切的植物群体中，性染色体分化变异的存在为性染色体起源的研究提供了模式系统。我们将对Silene中的Y染色体进行研究，以检验有关其结构、功能和进化发展的理论预测。为了追溯Y染色体的进化历史，将从用流式细胞仪分离的Y染色体中产生一系列基于DNA的遗传标记，然后用限制性内切酶进行消化。由此产生的Y特异的DNA探针将与宽叶狼尾草的中期染色体以及具有和不具有性别的近缘物种进行交叉杂交，期望Y染色体将有一些与X染色体相似的区域。非同源的光环用于防止重组，这将扰乱宽叶木兰的‘主动Y’性别决定。其次，宽叶木兰的Y染色体被认为存在部分功能障碍。Y染色体对花卉表型的影响的定量遗传分析将使用一系列关系(例如，父母：后代、祖父母：孙辈、同父异母等)的回归分析。这项研究将整合不同的方法，从分子细胞遗传学到数量遗传学，并将极大地增强我们对涉及性别分化的遗传事件的理解。

A stable genetic mechanism for sex determination is a prerequisite for the maintenance of separate sexes in a species. This in turn requires that those genes promoting or suppressing female and male expression be located on the same chromosome. Chromosomal sex determination, uncommon in plants, is widespread in animals and is almost invariably accompanies by morphological differentiation of the X and Y chromosomes. The relatively recent origin of sex chromosomes in plants means that, in many cases, closely related species which lack sex chromosomes, also exist. The existence of variation in sex chromosome differentiation within a closely related group of plants provide a model system for the study of the origin of sex chromosomes. The Y chromosomes in Silene will be studied as a test of theoretical predictions concerning their structure, function, and evolutionary development. To trace the evolutionary history of the Y, a collection DNA-based genetic markers will be generated from Y chromosomes isolated using flow cytometry and subsequently digested using restriction enzymes. The resulting Y-specific DNA probes will be cross-hybridized with metaphase chromosomes of S. latifolia as well as related species with and without separate sexes the expectation is that the Y chromosome will have some regions of similarity with the X . Auras of non-homology serve to prevent recombination that would disrupt the 'active Y' sex determination of S. latifolia. Second, the Y chromosome in S. latifolia is believed to be partially dysfunctional. A quantitative genetic analysis of Y chromosome effects on floral phenotypes will be using performed regressions over a range of degrees of relationship (e.g. parent: offspring, grandparent:grand-offspring, half-sib, etc.). This study will integrate diverse approaches, from molecular cytogenetics to quantitative genetics, and will greatly enhance our understanding of the genetic events involved in sex differentiation.