The gametophyte represents the sexual phase in the alternation of generations in plants; the other, nonsexual phase is the sporophyte. Here, we review the evolutionary origins of the male gametophyte among land plants and, in particular, its ontogenesis in flowering plants. The highly reduced male gametophyte of angiosperm plants is a two- or three-celled pollen grain. Its task is the production of two male gametes and their transport to the female gametophyte, the embryo sac, where double fertilization takes place. We describe two phases of pollen ontogenesis-a developmental phase leading to the differentiation of the male germline and the formation of a mature pollen grain and a functional phase representing the pollen tube growth, beginning with the landing of the pollen grain on the stigma and ending with double fertilization. We highlight recent advances in the complex regulatory mechanisms involved, including posttranscriptional regulation and transcript storage, intracellular metabolic signaling, pollen cell wall structure and synthesis, protein secretion, and phased cell-cell communication within the reproductive tissues. Expected final online publication date for the Annual Review of Plant Biology, Volume 72 is May 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

中文翻译：

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生殖多任务：雄配子体。

配子体代表植物世代交替中的有性相。另一个非性相是孢子体。在这里，我们回顾了陆地植物中雄配子体的进化起源，尤其是其在开花植物中的成因。被子植物的雄配子体高度减少，是两细胞或三细胞的花粉粒。它的任务是生产两个雄配子，并将它们运输到雌配子体，即胚囊，在那里进行双重受精。我们描述了花粉本体形成的两个阶段-一个发育阶段，导致雄性种系分化和成熟花粉粒的形成，一个代表花粉管生长的功能阶段，始于花粉粒在柱头上的着陆并结束双重受精。我们重点介绍了所涉及的复杂调控机制的最新进展，包括转录后调控和转录本存储，细胞内代谢信号传导，花粉细胞壁结构和合成，蛋白质分泌以及生殖组织内的分阶段细胞间通讯。《植物生物学年度评论》第72卷的最终最终在线发布日期为2021年5月。有关修订的估算，请参见http://www.annualreviews.org/page/journal/pubdates。