Plant carotenoid cleavage oxygenase (CCO) is an enzyme that catalyzes the synthesis of carotenoids and participates in many important physiological functions. The plant CCOs exist in two forms, namely carotenoid cleavage dioxygenase (CCD) and nine- epoxide carotenoid dioxygenase (NCED). Although studies have shown that this gene family has been identified in many species, such as , grape, and tomato, the evolutionary origin of the CCO family and the expression pattern of pepper genes in response to HO and other abiotic stresses are still unclear. In this study, we used the bioinformatics method to identify and analyze the members of the gene family from pepper and other 13 plants from lower to higher plant spe... More
Plant carotenoid cleavage oxygenase (CCO) is an enzyme that catalyzes the synthesis of carotenoids and participates in many important physiological functions. The plant CCOs exist in two forms, namely carotenoid cleavage dioxygenase (CCD) and nine- epoxide carotenoid dioxygenase (NCED). Although studies have shown that this gene family has been identified in many species, such as , grape, and tomato, the evolutionary origin of the CCO family and the expression pattern of pepper genes in response to HO and other abiotic stresses are still unclear. In this study, we used the bioinformatics method to identify and analyze the members of the gene family from pepper and other 13 plants from lower to higher plant species based on the whole genome sequence. A total of 158 genes were identified in different plant species and further divided into two groups (e.g., groups I and II). The former was subdivided into CCD7 and CCD8 and have independent evolutionary origins, respectively, while the latter was subdivided into CCD1, CCD4, CCD-like, and NCED, which may have come from a common ancestor. In addition, the results of RNA-seq showed that the expression patterns of pepper genes were different in the tissues tested, and only few genes were expressed at high levels such as , , , and . For hydrogen peroxide (HO) and other abiotic stresses, such as plant hormones, heat, cold, drought, and NaCl treatments, induction of about half of the genes was observed. Moreover, the expression patterns of CaCCOs were further investigated under heat, cold, drought, and NaCl treatments using quantitative real-time PCR (qRT-PCR), and most members were responsive to these stresses, especially some CaCCOs with significant expression changes were identified, such as , and , suggesting the important roles of CaCCOs in abiotic stress responses. All these results will provide a valuable analytical basis for understanding the evolution and functions of the CCO family in plants.
