Metabolome and Transcriptome Analysis Reveal the Accumulation Mechanism of Carotenoids and the Causes of Color Differences in Persimmon (Diospyros kaki Thunb.) Fruits

Abstract

To explore the mechanisms of the color formation of different colored persimmon fruits, we used two different colored persimmon cultivars (yellow-peeled persimmon fruit ‘Zhongshi No.6’ and red-peeled persimmon fruit ‘Hongdenglong’) as materials to study the synthesis and accumulation of carotenoids in three stages (full green, color transition, and full yellow or red) using targeted metabolomic and transcriptomic methods. A total of 14 carotenoids and 30 carotenoid lipids were identified in the peel of the two persimmon cultivars. After analysis, it was found that the total carotenoid content of the red persimmon cultivar was higher than that of the yellow persimmon cultivar. The contents of lycopene, α-carotenoid, β-carotenoid, (E/Z)-phytoene, and β-cryptoxanthin are the main reasons for the difference in total carotenoid content between the two persimmon cultivars, especially lycopene. Twelve structural genes involved in the metabolism of carotenoids were also found in this study. In comprehensive metabolome and transcriptome analysis, we found that, between the two persimmon cultivars, lycopene was the key metabolite responsible for the color difference, and PSY, LCYE, and ZDS were the key genes that regulated the differences in lycopene accumulation. The results of this study provide us with new information regarding persimmon fruit synthesis and accumulation. In addition, they also provide a theoretical foundation for improving persimmon fruit germplasm.