Transcriptomic and metabolite analyses provided a new sight of 1-MCP on organic acid metabolism in peach during storage.

In this study, "Xiahui 6" peaches were treated with 10 µL/L 1-methylcyclopropene (1-MCP) for 12 h and then stored at 20°C for 9 days; the regulation of 1-MCP on organic acids during storage was investigated through transcriptomic and metabolite analyses. Results showed that 1-MCP maintained higher gene expression of malate synthesis (PpPEPC1, PpPEPC2, and PpNAD-cytMDH) at the end of storage but extremely inhibited the gene expression of malate degradation (PpNADP-cytME) during storage, resulting that malate content in treated peaches was twice that of control group at day 7. Besides, the increasement of citrate synthesis and degradation-related genes (PpmitCS, PpcytACO, PpNAD-mitIDH, and PpNADP-cytIDH) at days 3 and 5 was postponed by 1-MCP treatment, accompanied by 0.5 times higher citrate content at day 7. Our results suggested that 1-MCP has inhibitory effects on both the synthesis and degradation of organic acids; however, the inhibitory effect of 1-MCP on organic acid degradation may be greater than that on organic acid synthesis. Practical Application: This study provides a theoretical basis for the application of 1-methylcyclopropene (1-MCP) in fruit preservation.

The regulation of 1-methylcyclopropene treatment on the subfamily genes expression of ethylene response factors in peaches during storage.

BACKGROUND: Ethylene response factors (ERFs) perform diverse functions in fruit development, ripening and senescence. However, the effects of postharvest treatments on ERF genes have not been widely investigated due to the lack of peach ERF genomic information. The aim of this study was to investigate the ERF genes' expression of freshly harvested peach during storage after 1-methylcyclopropene (1-MCP) treatment. METHODS: 10 µL L-1 1-MCP was used to fumigate peaches. Treated peaches and control peaches were stored at 20°C for 9 days. Fruit firmness, ethylene production and the transcript abundance of ERFs were evaluated during storage. RESULTS: 127 AP2/ERF genes were identified genome using RNA-sequencing (RNA-seq). Expression profiles of 39 ERF genes were considered at day 0, 3, 5 and 7. Results showed that 1-MCP inhibited some ERF genes' expression (e.g., Prupe.5G117800), some genes were generally up-regulated responding to 1-MCP (e.g., Prupe.6G039700), while the other ERF genes displayed no significant difference between the two groups (e.g., Prupe.1G130300). CONCLUSIONS: These data revealed that peach ERF genes perform diverse functions during fruit growth, ripening and senescence. The different responses of ERF genes to postharvest 1-MCP treatment may be useful to understand the roles of ethylene and ERF genes in controlling technological aspects of postharvest peach conservation.

The alleviation of methyl jasmonate on loss of aroma lactones correlated with ethylene biosynthesis in peaches.

Peaches are vulnerable to cold temperature, showing the symptoms of chilling injury (CI). The occurrence of CI results in irreversible aroma loss, especially 'peach-like' lactones loss during cold storage and subsequent shelf life. Methyl jasmonate (MeJA) treatment is effective in alleviating CI symptoms in peach fruit; however, its effect on peach aroma volatiles is still unknown. To explore the effect and mechanism of MeJA treatment on aroma loss of peaches, fruit was treated with 10 µmol/L MeJA, then stored at 4 °C for 3 weeks, and subsequently transferred to 20 °C to simulate shelf life for 3 days. Here, the ability of MeJA to regulate aroma lactones of 'Xiahui 6' peaches was investigated, and the expression of genes responsible for ethylene and lactones biosynthesis was considered. MeJA treatment significantly reduced internal browning index, increased ethylene production, and promoted the emission of aroma-related lactones in peaches during shelf life at room temperature. In addition, MeJA also elevated the expression of PpSAMS, PpACS3, PpACS4, PpACO, and PpACX3 during or after cold storage. These results suggested that MeJA treatment could enhance chilling tolerance in peaches and induce the recovery of ethylene and aroma lactones, which is closely related to ethylene biosynthesis as revealed by upregulated genes expression of PpSAMS, PpACS3/4, and PpACO. PRACTICAL APPLICATION: This research provides theoretical basis for the application of methyl jasmonate in fruit preservation and the basis for molecular breeding to cultivate aroma-abundant peach fruits.

Exogenous nitric oxide fumigation promoted the emission of volatile organic compounds in peach fruit during shelf life after long-term cold storage.

Cold temperature is a common method to store peach after harvest. While long-term cold storage leads to the occurrence of chilling injury and loss of volatile organic compounds (VOCs) after transferring peach to shelf life. Nitric oxide (NO) treatment has been proven to alleviate peach chilling injury. However, the effect of NO treatment on peach VOCs during cold storage plus shelf life is still unknown. In this study, 10 µL L-1 NO was used to fumigate peach before 4 °C cold storage. After cold storage for 21 days, peach were transferred to 20 °C for 3 days to simulate shelf life. Results showed that NO treatment promoted the emission of main VOCs including C6 aldehydes, C6 alcohols, straight-chain esters and lactones after cold storage, supported by the changes of fatty acids and genes expression of PpFADs, PpLOXs, PpHPL, PpADH, PpAATs and PpACXs. Besides, NO also alleviated the occurrence of chilling injury and promoted the recovery of respiration rate and ethylene production during shelf life. In conclusion, treatment with NO effectively prevented the loss of VOCs when transferring peach from cold temperature to shelf life in "Xiahui 6" peach and the possible mechanisms were discussed.

1-MCP treatment affects peach fruit aroma metabolism as revealed by transcriptomics and metabolite analyses.

1-methylcyclopropene (1-MCP) negatively affects peach aroma but the underlying molecular basis remains elusive. In this study, transcriptomics and metabolite analyses were carried out to investigate the regulatory mechanisms of 1-MCP on peach aroma from different standpoints: fatty acid (FA) metabolism, ethylene signal transduction and lipoxygenase/ß-oxidation pathway during 20 °C storage. Results indicate that 1-MCP significantly postponed the ethylene climacteric peak appearance and reduced ethylene production through down-regulation of related biosynthesis and signal transduction genes including PpaSAMS1/2, PpaACS1/2, PpaACO1 together with PpaETR1/2, PpaERS1, PpaEIN4 and PpaCTR1. Decrease in the levels of FAs and PpaFADs was observed in treated fruit, except oleic acid and PpaFAD4/5, before day 5 of storage. In addition, 1-MCP-treated fruit also possessed higher levels of C6 aldehydes and alcohols and delayed the formation of volatile compounds characteristic of peach-like aroma by upregulation of PpaLOX1/2/3 and PpaHPL1 expression and down-regulation of PpaLOX5 expression. Our findings suggest that inhibition of peach-like volatiles and promotion of green-note volatiles by 1-MCP were associated with ethylene production and modulation of FA levels through transcriptional regulation.

[Adjuvant treatment of acupoint catgut embedding for essential hypertension and its effects on vascular endothelial function].

OBJECTIVE: To observe the effects of acupoint catgut embedding assisting western medication and simple western medication on blood pressure and vascular endothelial function in patients with essential hypertension (EH), and to explore its mechanism. METHODS: A total of 125 cases were randomly assigned into an observation group (62 cases, 2 dropping) and a control group (63 cases, 3 dropping). Oral administration of lotensin (10 mg, once a day) was applied in the control group. Based on the treatment as the control group, acupoint catgut embedding was applied at Fengchi (GB 20), Ganshu (BL 18), Shenshu (BL 23), Quchi (LI 11), Zusanli (ST 36), Sanyinjiao (SP 6) and Taichong (LR 3) in the observation group, once every two weeks, and six treatments was taken as one session. All the patients were treated for 3 months. The blood pressure and the vascular endothelial injury markers, including endothelin-1 (ET-1), nitric oxide (NO), high sensitive C reactive protein (hsCRP) were recorded before and after treatment in the two groups. In addition, the ET-1, NO and hsCRP were collected from 60 cases of healthy participants. RESULTS: The diastolic blood pressure and systolic blood pressure reduced after treatment in the two groups (all P<0.05), which were more significant in the observation group (P<0.01, P<0.05). Before treatment, compared with those of the healthy participants, ET-1 and hsCRP were higher but NO was lower in the observation group and the control group (all P<0.05); after treatment, ET-1 and hsCRP were reduced and NO increased in the two groups (all P<0.05), which were more significant in the observation group (all P<0.05). After treatment, the differences of NO and hsCRP between the observation group and healthy participants were not significant (both P>0.05). The marked effective rate was 70.0% (42/60) in the observation group, which was superior to 33.3% (20/60) in the control group (P<0.05); the total effective rate was 96.7% (58/60) in the observation group, which was superior to 85.0% (51/60) in the control group (P<0.05). CONCLUSION: The vascular endothelial function is injured in EH patients. Based on lotensin treatment, acupoint catgut embedding could significantly improve blood pressure and vascular endothelial function.