Sprayable double-stranded RNA mediated RNA interference reduced enzymatic browning of fresh-cut potatoes

Abstract

Postharvest quality deterioration is the major reason for food loss and waste, which hinder global food security, environmental sustainability and human health. Spray-induced gene silencing (SIGS) is a technique involving spraying double-stranded RNA (dsRNA) onto the plant surface for targeted RNA interference, providing a new solution for pests and disease control in agriculture products. Here, fresh-cut browning, which is a common and visible quality deterioration in potatoes, was taken as the indicator for the exploratory SIGS technology in postharvest quality deterioration control. The polyphenol oxidase (PPO) encoding genes StPPO and StPPOD, and the phenylalanine ammonia-lyase (PAL) encoding gene StPAL2, were identified as important transcripts associated with the browning process in freshly-cut potatoes of the Yunshu 505 cultivar. Inhibition of StPPO and StPAL2 using dsRNA-PPO and dsRNA-PALX resulted in a decrease in the expression levels of the two genes, consequently leading to reduced activities of polyphenol oxidase and phenylalanine ammonia-lyase, as well as a decrease in the brown index. Spraying a mixture of these two dsRNAs demonstrated browning control capabilities similar to those of ascorbic acid. The distribution of dsRNA-Cy5 in cells confirmed its uptake and internalization by fresh-cut potatoes. In addition, the application of dsRNA-MYB12 resulted in a reduction of up to 78 % in tuber StMYB12 levels and decreased StPPO and StPAL1 expression. Spraying dsRNAs effectively reduced fresh-cut browning, highlighting the potential application of SIGS in reducing the browning of fresh-cut potatoes.