Changes in the carotenoids profile of two yellow-fleshed kiwifruit cultivars during storage

Carotenoid level in fruit changes dynamically in response to storage condition, however, the underlying mechanism remains unclear. Here, we investigated the carotenoid profiles and associated gene expression to reveal its responses to different storage temperature (20 degrees C and 4 degrees C) in two kiwifruit cultivars, bright-yellow-fleshed Jinshi 1 and pale-yellow-fleshed Jinyan. At harvest, four main carotenoids were detected in cv. Jinshi 1, while only three in cv. Jinyan, excluding beta-cryptoxanthin, which accounted for the majority of carotenoids in 'Jinshi 1'. Storage at 20 degrees C increased content of the total carotenoid and beta-carotene in both cultivars, and up-regulated the expression of biosynthesis gene PSY, but down-regulated the expression of carotenoid degradation genes CCD1 and NCED1. It also induced beta-cryptoxanthin and alpha-carotene production in Jinyan at later stage. On the contrary, storage at 4 degrees C decreased total carotenoid content, but induced the expression of carotenoid biosynthetic gene PDS, LCYB, LCYE. These results suggested expression of PSY, CCD1 and NCED1 plays an important role in improvement of carotenoids level at 20 degrees C. Furthermore, high proportion of beta-cryptoxanthin might contribute to yellower flesh in Jinshi 1.