Regulation Of Potato Cold-induced Sweetening By SbRFP1

Tubers are the only edible organ of potato. With changes in consumption habits,in addition to fresh consumption, processed products are increasingly accepted by consumers. In the potato processing industry, in order to extend shelf life and reduce the loss of storage due to high temperature, tubers are often stored at low temperatures.However, low temperature enhances the accumulation of reducing sugars in the tubers,which has seriously affected the quality of frying products. The present study explored the impact of the potato gene Sb RFP1 on cold-induced sweetening. The main results obtained are:1. Overexpression of the Sb RFP1 gene in potato resulted in an increase in starch content and decrease in reducing sugars, as well as an obviously improvement of the chip color, while the reverse was true in Sb RFP1 silenced tubers by RNA interference.Our results suggest that Sb RFP1 may have great potentials in improvement of potato cold-induced sweetening.2. Sb RFP1 is a RING finger protein with ubiquitin ligase activity. The results demonstrated the ubiquitination function loss of Sb RFP1 when its RING finger domain was mutated as Sb RFP1(H-T/ C-S).3. Tobacco transient expression showed that Sb RFP1 mainly localizes in the nucleus. The protein interaction experiment using Pull-down technology indicated that Sb RFP1 can directly interact with St Amy23 and St BAM1. It was reinforced in vitro that Sb RFP1 can influence the activity of amylases, especially β-amylase activity.However, the ELISA test showed there were no differences in the amount ofβ-amylase between Sb RFP1 transgenic and control tubers.These results suggest that, Sb RFP1 impacts on starch hydrolyzing enzymes,especially β-amylase activity to influence the accumulation of reducing sugars in potato tubers exposed to low temperature, ubiquitination degradation is unlikely involved but a non-degradation pathway may contribute to inhibit amylase.