外源褪黑素对采后西梅的贮藏品质及软化相关基因表达的影响

乔沛; 李慧星; 罗建成; 程爽; 于海彦

doi:10.13386/j.issn1002-0306.2024060076

外源褪黑素对采后西梅的贮藏品质及软化相关基因表达的影响

Effect of Exogenous Melatonin on Postharvest Storage Quality and Softening-Related Gene Expression of Prunus domestica

摘要

摘要: 目的：探究外源褪黑素处理对采后西梅果实贮藏品质和相关代谢的影响。方法：该研究分别以60、120和240 μmol/L的褪黑素（melatonin，MT）处理“四川广安”西梅果实作为处理组，并以清水处理为对照组，观察西梅果实在常温（22±3 ℃，65%±5% RH）贮藏过程中的果实色度、失重率、可溶性固形物（total soluble solid，TSS）含量、可溶性蛋白含量、细胞膜通透性、丙二醛（Malondialdehyde，MDA）含量等贮藏品质及相关代谢的变化。结果表明：关于果实色度方面，不同MT处理组的L^*和b^*值相对于对照组均无明显的差异（P>0.05），而c^*值在贮藏后期（9~12 d）具有明显差异（P<0.05），其中60和120 μmol/L MT处理组与对照组的差异最明显；关于贮藏品质方面，在贮藏中后期（6~12 d）不同MT处理组相对于对照组均显著抑制失重率的上升（P<0.05），其中60 μmol/L处理组效果最佳，同时不同MT处理组相对于对照组均可以有效抑制TSS含量的下降（P<0.05），其中240 μmol/L处理组效果最佳；关于西梅果实细胞膜结构方面，不同处理组相对于对照组均在贮藏中期（3~9 d）均可以有效抑制西梅果实细胞膜通透性和MDA含量的上升（P<0.05），其中60 μmol/L处理组效果最佳；关于西梅果实活性氧代谢方面，不同处理组相对于对照组均在贮藏后期（9~12 d）可以有效促进超氧化物歧化酶（superoxide dismutase，SOD）和过氧化物酶（peroxidase，POD）酶活性上升的（P<0.05），其中60 μmol/L处理组效果最佳；关于软化相关代谢方面，相对于对照组，不同MT处理组均抑制多聚半乳糖醛酸酶（polygalacturonase，PG）、β-半乳糖苷酶（β-galaetosidase，β-Gal）和纤维素酶（cellulase，Cx）的活性和PdPG2、PdCx6和Pdβ-GAL3相对表达量的上升，同时有效维持Pd PME31的表达量，但只有60 μmol/LMT组与CK组之间存在显著性差异（P<0.05），而120和240 μmol/L MT处理组却无显著差异（P>0.05）。最后，经过主成分分析，发现60 μmol/LMT处理相对于120和240 μmol/L MT处理具有更好的保鲜效果。结论：外源MT处理一方面可有效调控软化相关酶活性及相关基因的表达量，延缓贮藏期间果实软化，另一方面促进抗氧化酶活性的上升，减轻活性氧对细胞膜结构的破坏，最终达到延缓采后西梅果实货架期的目的。研究结果为采后外源褪黑素在采后果蔬中的应用提供理论依据。

Abstract: Objective:This study investigates the effects of exogenous melatonin treatment on the post-harvest quality and related metabolism of postharvest prune fruits. Methods: The "Sichuan Guang'an" prunes fruit with 60, 120 and 240 μmol/L melatonin (MT) were treated as the treatment groups, and water treatment was treated as the control group in this study.And the changes in storage quality and related metabolism of prunes fruit including color, weight loss rate, total soluble solid content (TSS), soluble protein content, cell membrane permeability and malondialdehyde (MDA) content were observed during room temperature (22±3 ℃, 65%±5% RH) storage. Results:The results showed that in terms of fruit color, there was no significant difference in L^* and b^* values between different MT treatment groups and the control group (P>0.05), while c^* values showed significant differences in the later stage of storage (9~12 days) (P<0.05), with the 60 and 120 μmol/L MT treatment groups showing the most significant differences compared to the control group. In terms of storage quality, during the later stages of storage (6~12 days), the increase in weight loss rate was inhibited significantly in different MT treatment groups relative to the control group (P<0.05), with the 60 μmol/L treatment group showing the best effect. At the same time, different MT treatment groups were able to effectively inhibit the decrease in TSS content relative to the control group (P<0.05), with the 240 μmol/L treatment group showing the best effect.While the decrease in TSS content inhibited effectively in different MT treatment groups compared to the control group (P<0.05), with the 240 μmol/L treatment group showing the best effect. Regarding the cell membrane structure of prunes fruit, the increase of cell membrane permeability and MDA content were inhibited effectively in different treatment groups of prunes fruit during the mid storage period (3~9 days) compared to the control group (P<0.05), with the 60 μmol/L treatment group showing the best effect. Regarding the metabolism of reactive oxygen species in prunes fruit, different treatment groups were found to effectively promote the increase of superoxide dismutase (SOD) and peroxidase (POD) enzyme activities during the late storage period (9~12 days) compared to the control group (P<0.05), with the 60 μmol/L treatment group showing the best effect.Regarding softening related metabolism, compared to the control group, the activities of polygalacturonase (PG), β-galactosidase (β-Gal), and cellulase (Cx) were all inhibited in different MT treatment groups, as well as the relative expression increase in the expression levels of PdPG2, PdCx6 and Pd β-GAL3. And the expression level of Pd PME31 was effectively maintained, but there was only a significant difference between the 60 μmol/L MT group and the CK group (P<0.05), while there was a significant difference between the 120 and 240 μmol/L MT treatment groups (P>0.05). Finally, after principal component analysis, it was found that the 60 μmol/L MT treatment had better preservation effect compared to the 120 and 240 μmol/L MT treatments. Conclusion: Exogenous MT treatment can effectively regulate the activity of softening related enzymes and the expression levels of related genes, delaying fruit softening during storage. On the other hand, it promotes the increase of antioxidant enzyme activity, reduces the damage of reactive oxygen species to cell membrane structure, and ultimately achieves the goal of delaying the shelf life of post harvest plum fruit. The research results provide a theoretical basis for the application of exogenous melatonin in post-harvest fruits and vegetables.