Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, 47907, USA.
Purdue Center for Plant Biology, Purdue University, West Lafayette, Indiana, 47907, USA.
Plant J. 2022 Jul;111(1):149-163. doi: 10.1111/tpj.15784. Epub 2022 May 12.
In contrast to seed plants, the gametophytes of seed-free plants develop pluripotent meristems, which promote and sustain their independent growth and development. To date, the cellular basis of meristem development in gametophytes of seed-free ferns remains largely unknown. In this study, we used Woodsia obtusa, the blunt-lobe cliff fern, to quantitatively determine cell growth dynamics in two different types of apical meristems - the apical initial centered meristem and the multicellular apical meristem in gametophytes. Through confocal time-lapse live imaging and computational image analysis and quantification, we determined unique patterns of cell division and growth that sustain or terminate apical initials, dictate the transition from apical initials to multicellular apical meristems, and drive proliferation of apical meristems in ferns. Quantitative results showed that small cells correlated to active cell division in fern gametophytes. The marginal cells of multicellular apical meristems in fern gametophytes undergo division in both anticlinal and periclinal orientations, not only increasing cell numbers but also playing a dominant role in increasing cell layers during gametophyte development. All these findings provide insights into the function and regulation of meristems in gametophytes of seed-free vascular plants, suggesting both conserved and diversified mechanisms underlying meristem cell proliferation across land plants.
与种子植物不同，无种子植物的配子体发育出多能性分生组织，促进和维持其独立的生长和发育。迄今为止，无种子蕨类植物配子体分生组织发育的细胞基础在很大程度上仍然未知。在这项研究中，我们使用钝叶叉蕨定量测定了两种不同类型的顶端分生组织——中央顶芽分生组织和配子体中的多细胞顶端分生组织中的细胞生长动态。通过共聚焦时程活体成像和计算图像分析和定量，我们确定了维持或终止顶芽的独特细胞分裂和生长模式，决定了从顶芽到多细胞顶端分生组织的转变，并驱动蕨类植物顶端分生组织的增殖。定量结果表明，小细胞与蕨类植物配子体中的活跃细胞分裂相关。蕨类植物配子体中多细胞顶端分生组织的边缘细胞以垂周和周向方向分裂，不仅增加了细胞数量，而且在配子体发育过程中对增加细胞层也起着主导作用。所有这些发现为无种子维管植物配子体分生组织的功能和调控提供了新的认识，表明分生组织细胞增殖在陆地植物中具有保守和多样化的机制。
