show Abstracthide AbstractFormative periclinal cell divisions are essential for three-dimensional body organization of land plants. GRAS transcription factor genes SHOOTROOT (SHR) regulates the formative periclinal cell division in the root of angiosperms. To understand the role of SHR in basal land plant lineage and infer the evolution of three-dimensional body organization in land plants, we tried to identify downstream genes of SHRs in the moss Physcomitrium patens (PpSHRs). To this end, we compared the transcriptomes of gametophore apices with leaf primordia and developing leaves, in which periclinal cell divisions take place, between wild type and the ppshr double mutant.