Department of Botany and Beaty Biodiversity Museum, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T 1Z4.
Philos Trans R Soc Lond B Biol Sci. 2022 May 9;377(1850):20210213. doi: 10.1098/rstb.2021.0213. Epub 2022 Mar 21.
Plants have characteristic features that affect the expression of sexual function, notably the existence of a haploid organism in the life cycle, and in their development, which is modular, iterative and environmentally reactive. For instance, primary selection (the first filtering of the products of meiosis) is via gametes in diplontic animals, but via gametophyte organisms in plants. Intragametophytic selfing produces double haploid sporophytes which is in effect a form of clonal reproduction mediated by sexual mechanisms. In homosporous plants, the diploid sporophyte is sexless, sex being only expressed in the haploid gametophyte. However, in seed plants, the timing and location of gamete production is determined by the sporophyte, which therefore has a sexual role, and in dioecious plants has genetic sex, while the seed plant gametophyte has lost genetic sex. This evolutionary transition is one that E.J.H. Corner called 'the transference of sexuality'. The iterative development characteristic of plants can lead to a wide variety of patterns in the distribution of sexual function, and in dioecious plants poor canalization of reproductive development can lead to intrasexual mating and the production of YY supermales or WW superfemales. Finally, plant modes of asexual reproduction (agamospermy/apogamy) are also distinctive by subverting gametophytic processes. This article is part of the theme issue 'Sex determination and sex chromosome evolution in land plants'.
植物具有影响性功能表达的特征,特别是在生命周期中存在单倍体生物,以及其模块化、迭代和环境反应的发育过程。例如,初级选择(减数分裂产物的第一次过滤)在二倍体动物中通过配子发生,但在植物中通过配子体生物发生。配子体内自交产生双倍体孢子体,这实际上是一种通过有性机制介导的无性繁殖形式。在同型孢子植物中,二倍体孢子体是无性的,只有在单倍体配子体中才表现出性。然而,在种子植物中,配子的产生时间和位置由孢子体决定,因此孢子体具有性的作用,在雌雄异株植物中有遗传性别,而种子植物配子体失去了遗传性别。这种进化转变是 E.J.H.科纳(E.J.H.Corner)所称的“性的转移”。植物的迭代发育特征可以导致性功能分布的多种模式,并且在雌雄异株植物中,生殖发育的不良疏导可能导致同性别交配和产生 YY 超雄或 WW 超雌。最后,植物的无性繁殖模式(无配子生殖/无配子生殖)也通过颠覆配子体过程而具有独特性。本文是主题为“陆地植物的性别决定和性染色体进化”的一部分。