Analysis of Cell Division Frequency in the Root Apical Meristem of Lycophytes, Non-seed Vascular Plants, Using EdU Labeling.

The organization of the root apical meristem (RAM) provides insights into the evolution of roots in vascular plants. The RAM of seed plants has a quiescent center (QC), in which the cells divide infrequently and function to maintain neighboring stem cells. However, the existence of a QC and the mechanisms of RAM maintenance in non-seed plants are poorly understood. We analyzed the RAM organization of lycophytes focusing on cell division activity using the EdU labeling method and showed that the RAM of Lycopodium species has a region with a very low cell division frequency, which was named the QC-like region. Here, we describe an in situ EdU labeling method for the RAM of growing roots in nature.