Gnetales have a key phylogenetic position in the evolution of seed plants. Among the Gnetales, there is an extraordinary morphological diversity of seeds, the genus Ephedra, in particular, exhibits fleshy, coriaceous or winged (dry) seeds. Despite this striking diversity, its underlying genetic mechanisms remain poorly understood due to the limited studies in gymnosperms. Expanding the genomic and developmental data from gymnosperms contributes to a better understanding of seed evolution and development. We performed transcriptome analyses on different plant tissues of two Ephedra species with different seed morphologies. Anatomical observations in early developing ovules, show that differences in the seed morphologies are established early in their development. The transcriptomic analyses in dry-seeded Ephedra californica and fleshy-seeded Ephedra antisyphilitica, allowed us to identify the major differences between the differentially expressed genes in these species. We detected several genes known to be involved in fruit ripening as upregulated in the fleshy seed of Ephedra antisyphilitica. This study allowed us to determine the differentially expressed genes involved in seed development of two Ephedra species. Furthermore, the results of this study of seeds with the enigmatic morphology in Ephedra californica and Ephedra antisyphilitica, allowed us to corroborate the hypothesis which suggest that the extra envelopes covering the seeds of Gnetales are not genetically similar to integument. Our results highlight the importance of carrying out studies on less explored species such as gymnosperms, to gain a better understanding of the evolutionary history of plants.

中文翻译：

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肉质或干燥：转录组分析揭示麻黄苞片发育的遗传机制

Gnetales 在种子植物的进化中具有关键的系统发育位置。在 Gnetales 中，种子具有非凡的形态多样性，特别是麻黄属，具有肉质、皮质或有翅（干燥）的种子。尽管存在这种惊人的多样性，但由于对裸子植物的研究有限，其潜在的遗传机制仍然知之甚少。扩展裸子植物的基因组和发育数据有助于更好地了解种子进化和发育。我们对具有不同种子形态的两种麻黄物种的不同植物组织进行了转录组分析。早期发育胚珠的解剖学观察表明，种子形态的差异在其发育早期就已建立。干种子加州麻黄和肉质麻黄抗梅毒的转录组学分析使我们能够确定这些物种中差异表达基因之间的主要差异。我们在抗梅毒麻黄的肉质种子中检测到几个已知参与果实成熟的基因。这项研究使我们能够确定参与两种麻黄种子发育的差异表达基因。此外，这项对加州麻黄和抗梅毒麻黄中具有神秘形态的种子的研究结果使我们能够证实这样的假设，即覆盖 Gnetales 种子的额外包膜在遗传上与外皮不相似。我们的研究结果强调了对较少探索的物种（如裸子植物）进行研究的重要性，