The Pepper Unconventional Prefoldin RPB5 Interactor Regulates Root and Hypocotyl Growth and Contributes to Heat Stress Tolerance

Plant Unconventional Prefoldin RPB5 Interactor (URI) proteins are key functional factors regulating plant growth, development, and stress responses, playing important roles in root morphogenesis, gravitropism regulation, and environmental stress signaling pathways. To investigate the biological function of the pepper URI gene, we identified the pepper URI homolog (CaURI) through sequence alignment and performed functional characterization using multiple molecular approaches. The pepper URI gene successfully rescued the shortened root length and impaired the root gravitropism phenotypes of the Arabidopsis uri-1 mutant. Subcellular localization revealed that the pepper URI protein was localized in the cytoplasm. Overexpression of pepper URI in Arabidopsis significantly inhibited root and hypocotyl elongation. RNA-seq analysis revealed that the expression patterns of many genes involved in growth and development were significantly altered in the CaURI-overexpressing Arabidopsis. Silencing of the endogenous pepper URI gene led to a marked reduction in plant height, and this dwarf phenotype was further aggravated under heat stress conditions. This work enriches the functional framework of the plant URI gene family and provides valuable genetic resources and a theoretical basis for dissecting the molecular mechanisms underlying pepper growth regulation and heat tolerance.