Wu Xiao, Yan An, McAdam Scott A M, Banks Jo Ann, Zhang Shaoling, Zhou Yun
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA.
Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, USA.
J Exp Bot. 2021 Oct 26;72(20):6990-7001. doi: 10.1093/jxb/erab307.
The alternation of generations in land plants occurs between the sporophyte phase and the gametophyte phase. The sporophytes of seed plants develop self-maintained, multicellular meristems, and these meristems determine plant architecture. The gametophytes of seed plants lack meristems and are heterotrophic. In contrast, the gametophytes of seed-free vascular plants, including ferns, are autotrophic and free-living, developing meristems to sustain their independent growth and proliferation. Compared with meristems in the sporophytes of seed plants, the cellular mechanisms underlying meristem development in fern gametophytes remain largely unknown. Here, using confocal time-lapse live imaging and computational segmentation and quantification, we determined different patterns of cell divisions associated with the initiation and proliferation of two distinct types of meristems in gametophytes of two closely related Pteridaceae ferns, Pteris vittata and Ceratopteris richardii. Our results reveal how the simple timing of a switch between two meristems has considerable consequences for the divergent gametophyte morphologies of the two ferns. They further provide evolutionary insight into the function and regulation of gametophyte meristems in seed-free vascular plants.
陆生植物的世代交替发生在孢子体阶段和配子体阶段之间。种子植物的孢子体发育出自我维持的多细胞分生组织，这些分生组织决定了植物的结构。种子植物的配子体缺乏分生组织，并且是异养的。相比之下，包括蕨类植物在内的无种子维管植物的配子体是自养且能独立生活的，它们发育出分生组织以维持自身的独立生长和增殖。与种子植物孢子体中的分生组织相比，蕨类植物配子体分生组织发育的细胞机制在很大程度上仍然未知。在这里，我们使用共聚焦延时活体成像以及计算分割和定量分析，确定了两种密切相关的凤尾蕨科蕨类植物——蜈蚣草和里氏水蕨配子体中与两种不同类型分生组织的起始和增殖相关的不同细胞分裂模式。我们的结果揭示了两种分生组织之间简单的转换时间如何对这两种蕨类植物不同的配子体形态产生重大影响。它们进一步为无种子维管植物配子体分生组织的功能和调控提供了进化方面的见解。
