Effect of storage temperature and light irradiation on respiration rate, red color development, and gene expression involved in carotenoid synthesis in green bell pepper (Capsicum annuum L.)

Bell pepper is a popular vegetable and a good source of beneficial elements for the human diet, such as vitamins, minerals, and carotenoids. The environmental condition surrounding the bell pepper is an important factor affecting its external and internal quality. During the external color change phase, the chlorophyll degradation and carotenoid synthesis is an important consumer attribute of green bell pepper after harvest. The objective of this study was to investigate the effect of storage temperatures (10, 20 and 30°C) and light irradiation on the quality, respiration rate and gene expression of fresh bell pepper. Measurements were conducted every five days throughout the storage period (25 days). The result showed that low storage temperature reduced the respiration rate and delayed the color development in green bell pepper. Light irradiation, stimulated the color change from green to red, when compared to the dark condition. Higher storage temperature and light irradiation showed high expression of the genes encoding phytoene synthase (CaPsy), ζ-Carotene desaturase (CaZds), β-carotene hydroxylase (CaCrtZ-2), and capsanthin/capsorubin synthase (CaCcs), involved in carotenoid synthesis. These findings indicate that high storage temperature combined with light irradiation stimulated carotenoid synthesis in harvested green bell peppers.