Regulation of carotenoid metabolism in Zinnia elegans by carotenoid cleavage dioxygenase

Zinnia elegans is an annual herbaceous ornamental flower, widely cultivated in domestic and foreign gardens due to its diversity in flower types, color and landscaping versatility . Petal color of Zinnia elegans ranges widely from red to orange and yellow due to different content of carotenoids and anthocyanins. β-carotene is the main carotenoid in the petals. However, how the carotenoid cleavage dioxygenase genes, which are closely related to β-carotene degradation, participate in carotenoid metabolism in Zinnia elegans ray florets and regulate the molecular mechanism of petal coloration in different color cultivars of Zinnia elegans is still unclear and should be further investigated.

Ornamental Plant Research published online a paper entitled “Carotenoid cleavage dioxygenase catalyzes carotenoid degradation and regulates carotenoid accumulation and petal coloration in Zinnia elegans” on 27 February 2024.

In this study, the total carotenoid content was determined in three Zinnia elegans cultivars Zinnia elegans 'Dreamland Red' (DRE), Zinnia elegans 'Dreamland Coral' (DC), and Zinnia elegans 'Dreamland Yellow' (DY), at four developmental stages. The results showed that the total carotenoid content was highest in DY petals but lowest in DRE. Subsequently,, three ZeCCDs (ZeCCD1, ZeCCD4-1 and ZeCCD4-2) were cloned from Zinnia elegans. The bacterial pigment complementation system was used to further characterize the carotenoid cleavage ability of these genes, which showed different cleavage activities against four carotenoids (β-carotene, ε-carotene, zeaxanthin, lycopene) in E.coli cells, with ZeCCD1 having the strongest cleavage activity. Meanwhile, the expression levels of ZeCCD1 and ZeCCD4-2 in the petals of different cultivars were significantly negatively correlated with the carotenoid content. In addition, the expression patterns and subcellular localization of ZeCCDs were analyzed. The results showed that ZeCCD1 is localized in the cytoplasm, whereas ZeCCD4-1 and ZeCCD4-2 are localized in the chloroplast,indicating that ZeCCD4-2 plays a more important role in carotenoid cleavage and petal coloration in Zinnia elegans.

In conclusion, this study underscores the function of ZeCCDs in cleaving β-carotene, ε-carotene, zeaxanthin and lycopene, as well as the relationship between the expression pattern and total carotenoid content in petals. It also highlights the important role of ZeCCD4-2 in carotenoid cleavage and lays a foundation for further research on the molecular mechanism of petal coloration and carotenoid metabolism of Zinnia elegans.

###

References

DOI

10.48130/opr-0024-0003

Original Source URL

https://doi.org/10.48130/opr-0024-0003

Authors

Hongsheng Qing, Xinyue Liu, Jiahong Chen, Li Li, Jieyu Qian, Jianxin Fu, Chao Zhang

Affiliations

Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, School of Landscape Architecture, Zhejiang Agriculture and Forestry University, Hangzhou 311300, Zhejiang, China

About Zhang Chao & Fu Jianxin 

Zhang Chao, an associate professor of Zhejiang Agriculture and Forestry University, is mainly engaged in the study on metabolism and regulation of flower color and scent in ornamental plants.

Fu Jianxin, an associate professor of Zhejiang Agriculture and Forestry University, is mainly engaged in the study on secondary metabolism in common zinnia and petunia.