| Nitric oxide(NO), a bioactive lipid soluble gas molecule, can pass through the cell membrane freely, and participate in a variety of physiological processes in organisms. Previous studies show that NO plays important roles in the metabolism of nitrite, reactive oxygen species(ROS) and some other physiological processes, especially in the ROS metabolism, which has been studied popularly. ROS in plant mostly origins from mitochondria. However, there is few reports about the relationship between NO and mitochondrial metabolisms in fruits during storage.In this paper, Feicheng peaches were treated with different NO solutions(5、15、30 μmol L-1) and c-PTIO solution(5 μmol L-1), and then were stored at 0 oC. The effects of NO on mitochondrial antioxidative system and mitochondrial membrane lipid metabolism in peach fruits during cold storage were studied.The results showed that 15 μmol L-1 NO treatment could delay the decrease in mitochondrial membrane permeability, besides that, 15 μmol L-1 NO treatment could decrease the content of mitochondrial ROS and improve the anti-oxidative enzymes in mitochondria. Among them, 15 μmol L-1 NO treatment improved mitochondrial SOD activity by 25.49%. Compared with the change of SOD activity, the effects of NO treatments on activities of CAT and POD was less obvious, while, the change trends of them was consistent with the change of ROS content and SOD activity. Then it can be suggested that NO could maintain the stability of anti-oxidative system in mitochondria of cold-stored Feicheng peach fruits via maintaining the mitochondrial membrane permeability, decreasing the ROS content and increasing the activities of anti-oxidative enzymes in mitochondria, for this paper, the suitable concentration was 15 μmol L-1 NO.During the cold storage of the peach fruits, chilling injury often occurs along with some other changes in different physiological activities. From the results of the experiments, it can be concluded that NO treatment could alleviate the chilling injury occurred during the storage. In the fourth week of the storage, the chilling injury index of 5 μmol L-1 NO treatment was 51.73% lower than that of the control group, while the chilling injury index of 15 μmol L-1 NO treatment was 62.71% lower than that of the control group. While the chilling injury index of the 30 μmol L-1 NO treatment was 20.69% higher than that of the control group. Besides, the results showed that, during the cold-storage, the proportion of unsaturated fatty acids(UFAs) in the total fatty acid were respectively : 60.08% in the first week, 58.95% in the second week, 58.90% in the fourth week and 23.56% in the fifth week, while the UFAs proportion of samples treated with 15 μmol L-1 NO was higher than that of other groups. Meanwhile, the mitochondrial MDA content in peach fruits treated with NO was lower, indicating that NO could alleviate the lipid peroxidadation. The decrease of mitochondrial LOX activity was benefit for easing the lipid peroxidadation too. In addition, ABA was detected from mitochondria of Feicheng peach fruit, via detecting ABA content of different treated peach fruits, we found that ABA content in mitochondria of fruits treated with 5 μmol L-1 NO was 11.87% lower than that of the control group, while that of the 15 μmol L-1 NO treatment was 30.52% lower than that of the control group. Then it can be suggested that NO might promote the maintaining of percentage of UFAs and inhibit the decrease of UFAs via lowering the activity of LOX in mitochondria, which led to the stability of membrane fluidity and resistance to cold. During the cold-storage of peach fruits, cold stress irritated the production of ABA in mitochondria, while, NO treatment could alleviate the damage of peach fruits during the cold-storage, therefore, there was a lower ABA content in mitochondria of peach fruits treated with NO. In conclusion, NO treatment could maintain the content of UFA and decrease the activity of mitochondrial LOX, resulting in the maintaining of membrane fluidity and the ability in resistance to cold, therefore, lowering the chilling injury level of the cold-storaged fruits. |
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