Transcription factor required for quiescent center cells specification and maintenance of surrounding stem cells, and for the asymmetric cell division involved in radial pattern formation in roots. Essential for cell division but not differentiation of the ground tissue. Also required for normal shoot gravitropism. Regulates the radial organization of the shoot axial organs. Binds to the promoter of MGP, NUC, RLK and SCL3. Restricts SHR movment and sequesters it into the nucleus of the endodermis. Interacts with SHR, JKD and MGP (PubMed:16640459, PubMed:17446396, PubMed:17785527, PubMed:18500650, PubMed:28211915). Interacts with SIEL (PubMed:21924907). Interacts with RBR1 through its the LxCxE motif (PubMed:22921914, PubMed:24302889). Expressed in siliques, leaves and roots. Detected in the initial daughter cell before its asymmetric division and remains expressed only in the endodermal cell layer after the division. Expressed in the endodermis or starch sheath of the seedling hypocotyl, in the leaf bundle sheath cells and the root quiescent center. Detected in the ground tissue of late heart-stage embryos. After germination, expressed also in the L1 layer throughout the shoot apical meristem including the peripheral zone. Detected in most tissues of young leaf primordia, except in the presumptive vasculature. In mature leaves, expressed in bundle sheath cells. Detected in inflorescence stems in a single internal cell layer corresponding to the starch sheath. Up-regulated by SHR and by itself. Plants have a greatly reduced root length and only a single cell layer between the epidermis and the pericycle. The sgrl-1 mutant has no gravitropic response either in inflorescence stems or in hypocotyls. Belongs to the GRAS family.