A novel gene, , negatively regulates fruit carotenoid content under cold stress in .

Background: Carotenoids, the secondary metabolites terpenoids, are the largest factors that form the fruit color. Similar to flavonoids, they are not only safe and natural colorants of fruits but also play a role as stress response biomolecules.

Methods: To study the contribution of the key genes in carotenoids biosynthesis, fruit-color formation, and in response to cold stress, we characterized the key regulatory factor from the HD-ZIP I sub-gene family members in pepper.

Results: Cold stress enhanced carotenoid accumulation as compared with the normal condition. silencing through virus-induced gene silencing changed the fruit color by regulating the carotenoid contents. silencing increased the antioxidant enzyme activities in the fruits of pepper, exposed to cold stress, whereas overexpression decreased the activities of antioxidant enzymes in the transgenic lines, exposed to cold stress, suggesting that is involved in the regulation of cold stress in the pepper fruits.

Conclusion: Our research will provide insights into the formation of fruit color in pepper and contribution of in response to cold stress. Further study should be focused on the interaction between and its target gene.