Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada.
Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
Philos Trans R Soc Lond B Biol Sci. 2022 May 9;377(1850):20210218. doi: 10.1098/rstb.2021.0218. Epub 2022 Mar 21.
Sex chromosomes in plants have often been contrasted with those in animals with the goal of identifying key differences that can be used to elucidate fundamental evolutionary properties. For example, the often homomorphic sex chromosomes in plants have been compared to the highly divergent systems in some animal model systems, such as birds, and therian mammals, with many hypotheses offered to explain the apparent dissimilarities, including the younger age of plant sex chromosomes, the lesser prevalence of sexual dimorphism, or the greater extent of haploid selection. Furthermore, many plant sex chromosomes lack complete sex chromosome dosage compensation observed in some animals, including therian mammals, some poeciliids, and , and plant dosage compensation, where it exists, appears to be incomplete. Even the canonical theoretical models of sex chromosome formation differ somewhat between plants and animals. However, the highly divergent sex chromosomes observed in some animal groups are actually the exception, not the norm, and many animal clades are far more similar to plants in their sex chromosome patterns. This begs the question of how different are plant and animal sex chromosomes, and which of the many unique properties of plants would be expected to affect sex chromosome evolution differently than animals? In fact, plant and animal sex chromosomes exhibit more similarities than differences, and it is not at all clear that they differ in terms of sexual conflict, dosage compensation, or even degree of divergence. Overall, the largest difference between these two groups is the greater potential for haploid selection in plants compared to animals. This may act to accelerate the expansion of the non-recombining region at the same time that it maintains gene function within it. This article is part of the theme issue 'Sex determination and sex chromosome evolution in land plants'.
植物的性染色体经常与动物的性染色体进行对比，目的是确定可以用来阐明基本进化特性的关键差异。例如，植物中通常同形的性染色体与一些动物模型系统（如鸟类和有胎盘哺乳动物）中高度分化的系统进行了比较，提出了许多假说来解释明显的差异，包括植物性染色体的年龄较年轻、性二态性的流行程度较低，或者单倍体选择的程度较大。此外，许多植物性染色体缺乏一些动物中观察到的完整性染色体剂量补偿，包括有胎盘哺乳动物、一些胎生鱂科鱼类和某些两栖动物，而植物的剂量补偿，如果存在的话，似乎也不完全。甚至性染色体形成的典型理论模型在植物和动物之间也略有不同。然而，在一些动物群体中观察到的高度分化的性染色体实际上是例外，而不是常态，许多动物类群在性染色体模式上与植物更为相似。这就引出了一个问题，即植物和动物的性染色体有何不同，以及植物的哪些许多独特特性预计会以不同于动物的方式影响性染色体进化？事实上，植物和动物的性染色体表现出更多的相似之处而不是差异，而且在性冲突、剂量补偿，甚至是分化程度方面，它们是否真的存在差异还远不清楚。总的来说，这两组之间最大的区别是植物中单倍体选择的潜力比动物大。这可能会加速非重组区域的扩张，同时保持其内部的基因功能。本文是主题为“陆地植物的性别决定和性染色体进化”的特刊的一部分。
