OsCYP22 Interacts With OsCSN5 to Affect Rice Root Growth and Auxin Signalling

ABSTRACT Beyond structural support, plant root systems play crucial roles in the absorption of water and nutrients, fertiliser efficiency and crop yield. However, the molecular mechanism regulating root architecture in rice remains largely unknown. In this study, a short‐root rice mutant was identified and named Oscyp22 . Oscyp22 showed impairment in the growth of primary, adventitious and lateral roots. Histochemical and fluorescent staining analyses revealed reduced cell elongation and division activity in the root of Oscyp22 . Further analysis showed that Oscyp22 displayed an impaired response to auxin treatment, indicating a disruption in the auxin signal transduction. Transcriptome analysis and auxin content measurement suggested that OsCYP22 might be involved in auxin synthesis and transport. Protein assays demonstrated that OsCYP22 could interact with OsCSN5 and induce its rapid degradation. Notably, Oscsn5 mutants also showed short root phenotypes and deficiencies in auxin response. These findings suggest that OsCYP22 plays a role in rice root growth potentially through auxin signalling and OsCSN5 stability.