Effec to finter action between internal ethyleneand 1-methylcyclopropene on ripening and cell wall components metabolism of tomato fruit | 内源乙烯与1-MCP互作对番茄成熟和细胞壁物质代谢的影响

صينى. 探讨内源乙烯与1-MCP的相互作用对贮藏过程中番茄成熟和细胞壁代谢的影响。将破色期番茄(“佛罗里达47”)果实分为4组，其中2组经低压低氧 (8 kPa,1.7 kPa O2) 处理6 h后，分别立即使用 50 μg/L液态1-MCP (HH+1-MCP)或去离子水(HH)浸泡1 min；另外2组未经HH处理的番茄果实,也分别使用50 μg/L 1-MCP (1-MCP)或去离子水(对照)浸泡1 min，测定处理后果实在贮藏(20 ℃)过程中成熟相关生理指标及细胞壁组分的变化。番茄果实经HH处理后，内源乙烯含量(IEC)急剧降低至对照水平的75.6%，且对1-MCP 的反应敏感性有所提高。HH+1-MCP处理显著抑制了果实硬度的下降，其硬度值在贮藏第4~16 天中，平均分别较对照和1-MCP处理高29.8%和15.6%；HH+1-MCP处理果实的呼吸和乙烯峰出现时间均较对照推迟4 d，较1-MCP处理推迟2 d，但对峰值影响未达到显著水平；与1-MCP处理相比，HH+1-MCP处理对多聚半乳糖醛酸酶(PG)、果胶甲脂酶(PME)、α-半乳糖苷酶(α-Gal)、β-半乳糖苷酶(β-Gal)等细胞壁降解酶活性的变化影响较大，对PG的影响尤为明显；HH+1-MCP处理还显著地抑制了番茄果实贮藏期水溶性和CDTA溶性糖醛酸 (UA)含量的增加，其水溶性UA 含量在贮藏的第6~12天平均值分别较对照和1-MCP 处理低37.3%和21.9%，其CDTA溶性UA含量在贮藏的第6~12天平均值分别较1-MCP处理果实低31.4% 和20.5%；凝胶渗透色谱分析结果显示，1-MCP 和HH+1-MCP处理延缓了番茄果实多聚糖醛酸分子的降解过程，且后者效果更为明显。此外，本试验HH处理各项测定指标与对照无显著差异。内源乙烯含量是调节1-MCP反应能力的重要因素，解释了不同跃变型果实在成熟起始后对1-MCP反应敏感性差异的原因。

إنجليزي. This study was to explore the effect of interaction between internal ethylene and 1-methylcyclopropene on ripening physiology of tomato fruit during postharvest storage. Breaker (cv. “Florida 47”) tomato fruits as a model system were divided into 4 groups, 2 groups of fruit were maintained under hypoxic hypobaric (HH, 8 kPa, 1.7 kPa O2) conditions for 6 h, followed immediately by treatment with sub-saturating levels (50 μg/L) of aqueous 1-MCP and di-water for 1 min at 20 ℃, respectively. Another 2 groups of fruits without prior to exposure to HH were treated 50 μg/L 1-MCP and di-water for 1 min at 20 ℃, respectively. After treatment, all fruits were stored at 20 ℃ and the ripening related physiological indexes as well as changes in cell wall metabolism components were investigated during storage. Upon removal from HH conditions, ethylene synthesis and internal ethylene concentration (IEC) were reduced 75.6% in breaker tomato fruits. Compared to control fruit and fruit receiving 50 μg/L aqueous 1-MCP without prior exposure to HH conditions, fruits subjected to HH conditions showed significantly enhanced 1-MCP efficacy on suppressing softening, in which the firmness in fruit treated with 1-MCP following HH was 29.8% and 15.6% higher that that in control and 1-MCP treated fruit during 4-16 d of storage; The respiration and ethylene peak in fruit treated with 1-MCP following HH was delayed by 4 and 2 d, respectively, compared with that in control and 1-MCP treated fruits, but no significant difference was found in climacteric maxima of respiration and ethylene production; The treatment with 1-MCP after HH also more evidently affected the activity trends of cell wall enzymes including polygalacturonase (PG), pectinmethylesterase (PME),α-galactosidase (α-Gal) and β-galactosidase (β-Gal) activity,typically on PG activity. Consistent with the trend of PG activity, water/CDTA soluble uronic acid (UA) content was strongly suppressed by treatment of 50 μg/L 1-MCP following HH, in which water soluble and CDTA soluble content UA in fruits treated with 1-MCP following HH were 37.3% and 31.4% lower than that in control, 21.9% and 20.5% lower than that in 1-MCPtreated fruits during 6-12 d of storage, respectively; Polyuronides in fruits treated with 1-MCP following HH exhibited slower molecular mass downshifts compared with the control and 1-MCP treated fruits. In addition, all results in this study showed that there were no significant differences between control and HH treatment. The results of this study offer further evidence that internal ethylene levels play a significant role in 1-MCP responsiveness and may explain the variable sensitivity of different climacteric fruits and cultivars to 1-MCP applied at and beyond the initiation of ripening.