The effect of diphenyliodonium iodide treatment on bisdemethoxycurcumin accumulation in fresh‐cut yam

Abstract

Yellowing is a main discoloration in fresh-cut yam, which reduces consumer acceptance and, hence, the commodity value. Bisdemethoxycurcumin has been demonstrated to play important roles in fresh-cut yam yellowing. Considering the pharmacological properties and application in fruits and vegetables of diphenyliodonium iodide (DPI), the effects and mechanism of DPI treatment on bisdemethoxycurcumin accumulation in fresh-cut yam were analysed. The results showed that total bisdemethoxycurcumin in freshcut yam treated with DPI was markedly inhibited due to the significantly weakened phenylpropanoid pathway and bisdemethoxycurcumin biosynthesis. DPI was found to suppress the activities of major enzymes (phenylalanine ammonia lyase, PAL, cinnamate-4 hydroxylase, C4H; 4-coumarate coenzyme A ligase, 4CL), limit the levels of PAL, C4H and 4CL transcription and lower the contents of related metabolites in fresh-cut yam. Moreover, treatment with DPI inhibitor restrained the downstream transcription level of curcumin synthase (CURS), which had a significant impact on bisdemethoxycurcumin synthesis. Thus, our results confirmed that DPI was essential for inhibiting bisdemethoxycurcumin accumulation in fresh-cut yam through suppressed phenylpropanoid pathway and bisdemethoxycurcumin biosynthesis.