摘要CELL DIVISION CONTROL PROTEIN48 (CDC48) is essential for membrane fusion, protein degrada-tion, and other cellular processes. Here, we re-vealed the crucial role of CDC48B in regulating periclinal cell division in roots by analyzing the recessive gen1 mutant. We identified the GEN1 gene through map-based cloning and verified that GEN1 encodes CDC48B. gen1 showed severely inhibited root growth, increased periclinal cell division in the endodermis, defective middle cortex (MC) formation, and altered ground tissue patterning in roots. Consistent with these pheno-types, CYCLIND 6;1(CYCD6;1), a periclinal cell di-vision marker, was upregulated in gen1 compared to Col-0. The ratio of SHRpro:SHR-GFP fluo-rescence in pre-dividing nuclei versus the ad-jacent stele decreased by 33% in gen1, indicating that the trafficking of SHORT-ROOT (SHR) de-creased in gen1 when endodermal cells started to divide. These findings suggest that the loss of function of CDC48B inhibits the intercellular traf-ficking of SHR from the stele to the endodermis, thereby decreasing SHR accumulation in the en-dodermis. These findings shed light on the crucial role of CDC48B in regulating periclinal cell division in roots.