Study On Mechanism Of Antioxidant System Regulating Storage Characteristics Of Sweet Potato

The people take food as the sky and food as the source.Food is the source of energy for human survival and the foundation for a country’s economic development.As a big country in crop production,China’s food production stability and output are basic and long-term goals.Post-harvest storage technology of agricultural products is one of the important guarantees for the adequate supply of food crops.However,during the postharvest storage process,due to the storage characteristics of the food crops,the annual losses due to improper storage after harvest are very serious.When the crops undergo aging,drought,cold and other biological processes during storage,the balance of free radical metabolism in the cells is imbalanced,and reactive oxygen species(ROS)accumulate in a large amount,causing lipid peroxidation of cell membranes,destroying cell results,and accelerating crop death.Sweet potato(Ipomoea batatas(L.)Lam.)is a grain and industrial raw material crop rich in starch and nutrients,and is also the top priority of China’s grain reserves.Sweet potato is usually harvested at the end of spring and late autumn.Due to the low temperature and storage characteristics,the post-harvest storage loss is very serious.Studies have confirmed that the antioxidant system in plants can effectively remove excess accumulated reactive oxygen species,weaken the damage caused by the accumulation of active oxygen,but the relationship between antioxidant system and crop storage characteristics and the antioxidant system respond to crop postharvest storage organisms.The mechanism of the process is still unclear.In this paper,postharvest sweet potato roots were used as experimental materials to analyze the relationship between antioxidant capacity and storage characteristics of sweet potato from physiological,biochemical and genetic levels,and to explore the response mechanism of sweet potato antioxidant system under low temperature stress,and analyze sweet potato from transcription level.The changes of metabolism and pathway under low temperature stress and the differential expression of low temperature stress response genes indicated that glutathione-S-transferase(GSTs)may play a key role in the resistance of sweet potato to low temperature stress.Subsequently,a tomato GST gene silencing vector was constructed to explore its function under cold stress.The experimental results showed that the antioxidant enzyme activity was positively correlated with the storability of sweet potato,but negatively correlated with ROS metabolite content and LOX activity.At the same time,under low temperature stress,the activity of sweet potato antioxidant enzymes was rapidly enhanced by low temperature induction at the initial stage of storage.Thereafter,the content of ROS metabolites increased dramatically due to the gradual loss of ROS scavenging enzymes.The storageresistant sweet potato variety has higher antioxidant enzyme activity,higher antioxidant metabolite content and lower ROS metabolite content,indicating the ability of antioxidant enzymes and antioxidants to scavenge ROS and the tolerance of sweet potato to low temperature stress.closely related.Through transcript level analysis,it was found that glutathione-S-transferase may play an important role in the response of sweet potato to low temperature stress.Tomato GST gene silencing plants are more sensitive to cold stress,and their ROS metabolites are higher than wild type.It is confirmed that the GST gene reduces the damage of plants due to chilling damage through its antioxidant and stress resistance.