Identification and expression analysis of the NCED gene family under abiotic stresses in barley (Hordeum vulgare L.)

As a rate-limiting enzyme in the abscisic acid (ABA) biosynthesis pathway, 9-cis-epoxycarotenoid dioxygenase (NCED) plays a crucial role in plant development and stress response by regulating ABA synthesis. In this study, we conducted a comprehensive bioinformatic analysis of the NCED gene family in barley (Hordeum vulgare L.), focusing on their physicochemical properties, secondary structures, conserved domains, genomic organization, and expression patterns. The results revealed the presence of 12 HvNCED genes in the barley genome, which are distributed across all chromosomes except chromosome 7. All HvNCED proteins were predicted to be hydrophilic, exhibit highly similar physicochemical properties, and contain the conserved RPE65 domain essential for enzymatic activity. Phylogenetic analysis demonstrated that the barley NCED members exhibit close evolutionary relationships with those in rice (Oryza sativa L.). Gene ontology (GO) enrichment analysis suggested that the HvNCED family is primarily involved in carotenoid catabolic processes via oxidoreductase activity. Additionally, cis-regulatory elements analysis identified numerous abiotic stress-responsive elements within the promoter regions of HvNCEDs. Consistent with these findings, qRT-PCR analysis confirmed that multiple HvNCED genes are transcriptionally activated under various abiotic stress conditions, highlighting their potential involvement in stress adaptation. Together, these results provide a solid foundation for future functional characterization of the HvNCEDs in barley.