Ranjan Aashish, Townsley Brad T, Ichihashi Yasunori, Sinha Neelima R, Chitwood Daniel H
Department of Plant Biology, University of California at Davis, Davis, California, United States of America.
Donald Danforth Plant Science Center, St. Louis, Missouri, United States of America.
PLoS Genet. 2015 Jan 8;11(1):e1004900. doi: 10.1371/journal.pgen.1004900. eCollection 2015 Jan.
Convergent morphologies have arisen in plants multiple times. In non-vascular and vascular land plants, convergent morphology in the form of roots, stems, and leaves arose. The morphology of some green algae includes an anchoring holdfast, stipe, and leaf-like fronds. Such morphology occurs in the absence of multicellularity in the siphonous algae, which are single cells. Morphogenesis is separate from cellular division in the land plants, which although are multicellular, have been argued to exhibit properties similar to single celled organisms. Within the single, macroscopic cell of a siphonous alga, how are transcripts partitioned, and what can this tell us about the development of similar convergent structures in land plants? Here, we present a de novo assembled, intracellular transcriptomic atlas for the giant coenocyte Caulerpa taxifolia. Transcripts show a global, basal-apical pattern of distribution from the holdfast to the frond apex in which transcript identities roughly follow the flow of genetic information in the cell, transcription-to-translation. The analysis of the intersection of transcriptomic atlases of a land plant and Caulerpa suggests the recurrent recruitment of transcript accumulation patterns to organs over large evolutionary distances. Our results not only provide an intracellular atlas of transcript localization, but also demonstrate the contribution of transcript partitioning to morphology, independent from multicellularity, in plants.
趋同形态在植物中多次出现。在非维管植物和维管陆地植物中，出现了根、茎和叶形式的趋同形态。一些绿藻的形态包括固着器、柄和叶状叶状体。这种形态出现在管藻目藻类中，它们是单细胞，不存在多细胞性。在陆地植物中，形态发生与细胞分裂是分开的，陆地植物虽然是多细胞的，但有人认为它们表现出与单细胞生物相似的特性。在管藻目的单个宏观细胞内，转录本是如何分配的，这能告诉我们关于陆地植物中类似趋同结构的发育情况什么信息呢？在这里，我们展示了一种从头组装的、针对巨大多核细胞杉叶蕨藻的细胞内转录组图谱。转录本从固着器到叶状体顶端呈现出一种整体的、基部到顶端的分布模式，其中转录本的身份大致遵循细胞内遗传信息的流动，即转录到翻译。对一种陆地植物和杉叶蕨藻转录组图谱交叉部分的分析表明，在漫长的进化距离中，转录本积累模式反复被招募到器官中。我们的结果不仅提供了转录本定位的细胞内图谱，还证明了转录本分配对植物形态的贡献，这种贡献独立于多细胞性。
