Study Of Sugar Metabolism During Low Temperature Storage And Rewarming Of Potatoes

Potato(Solanum tuberosum L.)is one of the most important non grain food crops in the world and has a significant impact on global food security.Potato consumption is gradually shifting from fresh food based rough processing to high value-added products.To ensure the supply of raw materials,potato tubers are usually stored at low temperatures(not exceeding 10 ℃)after harvest,but low temperatures can lead to the accumulation of reducing sugars in potato tubers,leading to low-temperature saccharification.The high content of reducing sugar in potatoes will cause Maillard reaction during high-temperature processing,produce melanoids and acrylamide,which will have a negative impact on the quality and food safety of potatoes after processing.Therefore,effective control of the accumulation of reducing sugars in potatoes during low-temperature storage will be beneficial in reducing the economic value and nutrient loss of potatoes during storage,preservation,and processing.This study used the "Hisen 6" potato as the experimental material and stored it at different temperatures(15 ℃ and 4 ℃).After 30 days of low-temperature storage,the samples were subjected to temperature recovery treatment.The weight loss rate,hardness,color difference value,germination rate,soluble sugar content,starch content,and changes in the expression of key genes in the starch sugar metabolism pathway were measured to explore the saccharification mechanism of potatoes at low temperature and temperature recovery.Previous studies have shown that St BAM1 is a key gene regulating low-temperature saccharification in potato tubers,and screening the transcription factors and their regulatory patterns that regulate St BAM1 in potatoes is the key to analyzing low-temperature saccharification in potatoes.This study will combine real-time fluorescence quantitative PCR,GUS reporter gene activity detection,and transient overexpression experimental technology systems to screen transcription factors that can regulate the key gene St BAM1 for low-temperature glycation,and verify its function.The specific research results are as follows:1.Low temperature storage delays the decrease in weight loss and firmness of potatoes,effectively extending their shelf life;However,low-temperature storage can also significantly increase the soluble sugar content and decrease the starch content in potato tubers,leading to a deepening of the color of fried potato chips and seriously affecting the processing quality;The rewarming treatment can effectively slow down saccharification,but the germination rate is too high when the rewarming temperature exceeds 20 ℃.Therefore,the 20 ℃ rewarming treatment for 6 days is selected.This rewarming system can significantly reduce the accumulation of soluble sugars,increase the generation of starch content,and restore the color of fried potato chips to bright yellow,greatly improving the processing quality of potatoes.2.After being warmed for 6 days at 20 ℃,potato tubers effectively slow down the occurrence of saccharification in potato tubers by upregulating the adenosine diphosphate glucose pyrophosphorylase St AGPase and downregulating the gene expression of starch hydrolase St BAM1/9 and St AMY23,inhibiting starch decomposition and accelerating starch biosynthesis.At the same time,the rewarming treatment also induced significant down-regulation of sucrose synthase St Su Sy and sucrose invertase St INV1 gene expression,which reduced the rate of sucrose synthesis in tubers and inhibited sucrose decomposition,effectively delaying the onset of glycation in tubers and improving the processing quality of potato.3.On the premise of clarifying the function of St BAM1,combined with the previous transcriptome data of the research group,the transcription factors with high correlation coefficient with the expression of St BAM1 were further screened using RT-q PCR technology,and the transcription factors St ABR1 and StbHLH074 that were consistent with the change trend of St BAM1 during low-temperature storage were obtained.This was then verified by PLANTCARE online prediction software and GUS reporter gene activity assay,which revealed that both transcription factors St ABR1 and StbHLH074 activate promoter St BAM1 activity.Compared with the control group,the soluble sugar content in the leaves of ordinary tobacco overexpressing St ABR1 and StbHLH074 significantly increased,while the starch content significantly decreased.The expression of key genes for sugar metabolism,Nt BAM1 and Nt INV,was significantly upregulated,indicating that the transcription factors St ABR1 and StbHLH074 combined with St BAM1 positively regulated the process of sugar metabolism.