Tetraspanin OsTET8 acts as a negative regulator of root development in rice.

Tetraspanins (TETs) are evolutionarily conserved transmembrane scaffolding proteins that play crucial roles in plant development, reproduction, and stress responses. However, their functions in rice root development remain poorly understood. Here, we characterized OsTET8, a rice TET family member, which displays root-specific expression in rice and predominantly localizes to the root elongation zone. Subcellular localization revealed that OsTET8 is dual-targeted to the endoplasmic reticulum (ER) and plasma membrane. OsTET8 knockout mutants exhibited significantly elongated primary roots, increased lateral root density, and enhanced adventitious root formation, whereas root-specific overexpression suppressed these characteristics. Furthermore, cytological analyses showed reduced root cross-sectional area and cortical cell layers in both knockout mutants and overexpression lines, indicating impaired cell proliferation. Transcriptomic profiling identified differentially expressed genes (DEGs) involved in intracellular redox homeostasis and jasmonic acid (JA) biosynthesis/signaling, which were further validated by qRT-PCR. Together, our findings demonstrate that OsTET8 negatively regulates rice root development, potentially through its coordination of redox homeostasis and JA signaling pathways. This study provides new insights into the molecular mechanisms underlying TET-mediated root development and highlights OsTET8 as a potential target for rice improvement.