Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
Curr Biol. 2017 Mar 6;27(5):R191-R197. doi: 10.1016/j.cub.2017.01.052.
Sex determination is as important for the fitness of plants as it is for animals, but its mechanisms appear to vary much more among plants than among animals, and the expression of gender in plants differs in important respects from that in most animals. In this Minireview, I provide an overview of the broad variety of ways in which plants determine sex. I suggest that several important peculiarities of plant sex determination can be understood by recognising that: plants show an alternation of generations between sporophytic and gametophytic phases (either of which may take control of sex determination); plants are modular in structure and lack a germ line (allowing for a quantitative expression of gender that is not common in animals); and separate sexes in plants have ultimately evolved from hermaphroditic ancestors. Most theorising about sex determination in plants has focused on dioecious species, but we have much to learn from monecious or hermaphroditic species, where sex is determined at the level of modules, tissues or cells. Because of the fundamental modularity of plant development and potentially important evolutionary links between monoecy and dioecy, it may be useful to relax the distinction often made between 'developmental sex determination' (which underpins the development of male versus female flowers in monoecious species) and 'genetic sex determination' (which underpins the separation of males and females in dioecious species, often mediated by a genetic polymorphism and sex chromosomes). I also argue for relaxing the distinction between sex determination involving a genetic polymorphism and that involving responses to environmental or hormonal cues, because non-genetic cues might easily be converted into genetic switches.
性别决定对植物的适应性与动物同样重要，但植物的性别决定机制似乎比动物更为多样化，而且植物的性别表现与大多数动物有很大的不同。在这篇综述中，我概述了植物决定性别方式的广泛多样性。我认为，通过认识到以下几点，可以更好地理解植物性别决定的几个重要特征：植物在孢子体和配子体阶段之间存在世代交替（其中任何一个阶段都可能控制性别决定）；植物在结构上是模块化的，缺乏生殖系（允许性别表现出一种在动物中不常见的定量表达）；植物的雌雄同体最终是从雌雄同体祖先进化而来的。大多数关于植物性别决定的理论都集中在雌雄异株物种上，但我们还有很多东西需要从雌雄同株或雌雄同体物种中学习，在这些物种中，性别是在模块、组织或细胞水平上决定的。由于植物发育的基本模块化以及雌雄同体和雌雄异株之间可能存在重要的进化联系，因此放松通常在“发育性别决定”（支持雌雄同株物种中雄性与雌性花的发育）和“遗传性别决定”（支持雌雄异株物种中雄性和雌性的分离，通常由遗传多态性和性染色体介导）之间的区别可能是有用的。我还主张放松涉及遗传多态性的性别决定与涉及对环境或激素线索的反应之间的区别，因为非遗传线索很容易转化为遗传开关。
