Postharvest Light Irradiation Induces Anthocyanin Accumulation in Fresh-Cut Lily Bulb (Lilium davidii var. unicolor) Scales

Abstract

During the storage and processing time of the lily bulb, violet-red discoloration of the scales often occurs, which is mainly caused by the biosynthesis of anthocyanin. To investigate the effect of light irradiation on the accumulation of anthocyanin in fresh-cut lily bulb scales, here, we examined the effect of 12 days of light irradiation and shading at 20°C on the accumulation of anthocyanin. We found that the violet-red color change of the lily bulb scales treated with 20°C/light irradiation was greater than that of the scales subjected to 20°C/shading treatment. This difference was based on variations in the L^∗, a^∗, and b^∗ values, as well as the degree of browning on the surface of the scales. The anthocyanin content in fresh-cut lily bulb scales treated with light irradiation was 5.08 times higher than that in the shaded treatment on Day 6, and this higher content persisted until Day 12. The activities of chalcone synthase (CHS), chalcone isomerase (CHI), dihydroflavonol reductase (DFR), and anthocyanin synthase (ANS) which belong to the anthocyanin synthetases family were enhanced by light irradiation treatment. RT-qPCR analysis showed that the expression of CHS, CHI, DFR, and ANS was consistent with enzyme activity. Furthermore, light irradiation increased the expression of HY5. Thus, these results suggested that light irradiation treatment induced the accumulation of anthocyanins in fresh-cut lily bulb scales to a greater extent than shadowing treatment. These results will contribute to understanding the mechanism of violet-red color change induced by light irradiation in lily bulbs.