Removal of ethylene: Oxidation
• Potassium permanganate
– Effective, cheap, air must pass through – Possible disposal problem, stains – Active ingredient of Purafil, sachets
– Activated charcoal – Brominated charcoal – Molecular sieves
• Effective in laboratory tests • Of little commercial use • Absorb many organic molecules
4、生产实际中，乙烯的利用及控制 •催S熟ea中l roSohmot system
• Add ethylene (gas, acetylene, ripening fruit) • Ventilate room regularly (12 - 24 hours) • Reapply ethylene after ventilation
无影响
• 乙烯对呼吸影响
一次
• 自身催化
一旦开始，不能停止
非跃变型
整个发育过程 浓度高，峰值大 多次处理，多次高峰 停止 乙烯，停止影响
（2）、乙烯生理作用的调控
CO2、降冰片二烯（norbornadiene，NBD)、环辛 烯 、 银 离 子 （ Ag+ ） 、 重 氮 基 环 戊 二 烯 （ diazocyclopentadiene, DACP ） 、 环 丙 烯 （ cyclopropene, CP ） 、 1- 甲 基 环 丙 烯 （1methylcyclopropene,1-MCP）和3，3-二甲基环丙烯 （3，3-methylcyclopropene,3，3-MCP）等，或是 乙烯作用的拮抗剂，或是乙烯信号转导的阻断剂。
• 其他调控乙烯生物合成的因子还有：自由基、 水杨酸（SA）、茉莉酸（JA）等。自由基则 作用于ACC向乙烯的转化。
• SA即邻羟基苯甲酸。抑制乙烯的生成。
• 自由基促进乙烯的生成。
• 茉莉酸，采后抑制。
•
3、 乙烯的生理作用及其调控
• （1）、生理作用
•
跃变型
• 显效时间
呼吸跃变前
• 乙烯浓度与呼吸高峰峰值
– Accelerates ripening – Causes abscission
• A problem:
– Accelerates ripening – Accelerates senescence – Causes abscission
Where does ethylene come from?
• Johns (Oxford)
– Isolation of ACC oxidase
甲硫 基核 糖
5—甲 硫腺 苷
2-酮基-4甲硫基丁 酸
AOA
AVG
促
EDTA
进
KCN
抑制
氧气 促进 催熟
嫌气性代谢 非偶联物 二氧化碳 温度>35Č
抑制
SAM在ACC合成酶催化下合成ACC的同时， 生成5-甲硫基腺苷（MTA），MTA 经水解后 转化成5-甲硫基核糖（MTR），MTR的甲硫基 裂解成核糖和甲硫基，而后进入Met，实现了 Met的循环利用。
• Drive air through the boxes • Suction or pressure
Ethylene
Overcoming ethylene effects
• Avoidance • Removal • Inhibition of production • Inhibition of action • Germplasm selection/engineering
– ‘Endless summer’ tomato (DNAP)
Ethylene
Ethylene
Trickle（缓慢添加） system
• Provide room with 1 air exchange/hour • Add ethylene continuously, 10 ppm • Flow meter, sight glass
Ethylene
Forced air ripening
– (above building, at night) • One air exchange/hour • Fan and cooling cost is minimal
Removal of ethylene: Absorption
• Molecules absorbed by molecular traps
• Ripening fruits • Smoke • Illuminating gas • Vehicle exhausts • Ripening rooms
Characteristics of ethylene responses
• Threshold concentration (0.1 ppm) • Plateau concentration (10 ppm) • Associated respiration rise • Temperature optimum (15 - 25 C) • CO2 (>1%) inhibits
• Catalytic oxidation (Swingtherm)
– Very effective – Very expensive
• Molecular oxidation
– With U.V. lamps – Apparently effective – Not yet generally available in commerce – Titanium dioxide - BioKES
•
• ACC氧化酶是作用于由ACC向乙烯合成的过 程。已知ACC氧化酶是一种膜结合蛋白质， 对各种处理不稳定，极易受破坏。
• ACC氧化酶并不是乙烯生成的限速步骤。一 般来说，环境因子对乙烯生成的影响是通过 调节ACC合成酶活性实现的。
• 外源多胺处理可以抑制伤乙烯的生成。
• AVG 和AOA是ACC合成酶活性的强烈抑制 剂，AOA和AVG处理香石竹切花，可以抑制 其乙烯的生成，并延长切花寿命。
Removal of ethylene: Oxidation
• Potassium permanganate
– Effective, cheap, air must pass through – Possible disposal problem, stains – Active ingredient of Purafil, sachets
away
Overcoming ethylene effects: Removal
• Ventilation • Hypobaric storage • Absorbtion • Oxidation
Removal of ethylene: Ventilation
• By far the easiest and cheapest • Requires source of ethylene-free air
Abscission of snapdragon（金鱼草） flowers in response to ethylene shows a typical threshold and
plateau response
2、Ethylene biosynthesis -A biochemical whodunit
Prototype U.V.
scrubber
Avoiding ethylene effects: Inhibition of biosynthesis and action
• Inhibitors of synthesis - AOA, AVG • Inhibitors of action - STS, 1-MCP • Inhibitors of both synthesis and action - High
• Catalytic oxidation (Swingtherm)
– Very effective – Very expensive
Removal of ethylenate
– Effective, cheap, air must pass through – Possible disposal problem, stains – Active ingredient of Purafil, sachets
• Lieberman (Beltsville)
– Methionine stimulates ethylene production
• Yang (Davis)
– S-Adenosylmethionine an intermediate （中间产物）
• Adams & Yang (Davis)
– 1-aminocyclopropane-1-carboxylic acid the ethylene precursor
Overcoming ethylene effects: Avoidance
• Don't mix sensitive and producing commodities • Isolate or ventilate ripening rooms • Keep internal combustion engines and smokers
• •
Veen, 1978
•
Bleeker, 1988 •
Fruit ripening – Smoky rooms, ripening fruit Scarification of figs （伤促进成熟） – Wound ethylene Ethylene gas - plant growth regulator Ethylene causes ripening