Developmental analyses of divarications in leaves of an aquatic fern <i>Microsorum pteropus</i> and its varieties

Plant leaves occur in diverse shapes. Divarication patterns that develop during early growths are one of key factors that determine leaf shapes. We utilized leaves of Microsorum pteropus, a semi-aquatic fern, and closely related varieties to analyze a variation in the divarication patterns. The leaves exhibited three major types of divarication: no lobes, bifurcation, and trifurcation (i.e., monopodial branching). Our investigation of their developmental processes, using time-lapse imaging, revealed localized growths and dissections of blades near each leaf apex. Restricted cell divisions responsible for the apical growths were confirmed using a pulse-chase strategy for EdU labeling assays.植物叶片的形态丰富多样。在早期生长阶段形成的分叉模式，是决定叶片形态的关键因素之一。本研究以半水生蕨类星蕨（Microsorum pteropus）及其近缘变种的叶片为材料，分析其分叉模式的变异特征。观测结果显示，这些叶片存在三类主要分叉类型：无裂片、二分叉与三叉分叉（即单轴分枝）。我们通过延时成像技术对叶片发育过程进行追踪，发现每个叶尖附近的叶片组织会发生局部生长与裂解。进一步通过5-乙炔基-2'-脱氧尿苷（EdU）标记的脉冲追踪（pulse-chase）实验，证实了负责叶尖生长的细胞分裂受到严格的区域调控。