Molecular Characteristics and Expression Patterns of Carotenoid Cleavage Oxygenase Family Genes in Rice ( Oryza sativa L.)

Carotenoid cleavage oxygenases (CCOs) cleave carotenoid molecules to produce bioactive products that influence the synthesis of hormones such as abscisic acid (ABA) and strigolactones (SL), which regulate plant growth, development, and stress adaptation. Here, to explore the molecular characteristics of all members of the OsCCO family in rice, fourteen family genes were identified in the genome-wide study. The results revealed that the OsCCO family included one OsNCED and four OsCCD subfamilies. The OsCCO family was phylogenetically close to members of the maize ZmCCO family and the SbCCO family. A collinearity relationship was observed between and in rice, as well as and between rice and , and maize. OsCCD4a and OsCCD7 were the key members in the protein interaction network of the OsCCO family, which was involved in the catabolic processes of carotenoids and terpenoid compounds. miRNAs targeting family members were mostly involved in the abiotic stress response, and RNA-seq data further confirmed the molecular properties of family genes in response to abiotic stress and hormone induction. qRT-PCR analysis showed the differential expression patterns of members across various rice organs. Notably, showed relatively high expression levels in all organs except for ripening seeds and endosperm. , , , , , , and were potentially involved in plant growth and differentiation. Meanwhile, , , , , and were associated with reproductive organ development, flowering, and seed formation. , , , , and were related to assimilate transport and seed maturation. These findings provide a theoretical basis for further functional analysis of the OsCCO family.