一氧化氮和外源乙烯处理对肥城桃果实乙烯生物合成的影响

 【目的】研究一氧化氮（NO）和乙烯处理对肥城桃内源乙烯生物合成的影响，并探讨NO与乙烯的拮抗作用。【方法】分别用10 μl?L-1 NO和1 000 μl?L-1 外源乙烯、10 μl?L-1 NO和1 000 μl?L-1 外源乙烯共同处理3种方式处理肥城桃果实，研究果实内源乙烯生物合成的变化。【结果】外源乙烯促进了肥城桃果实的内源乙烯生物合成；而NO通过显著降低果实中ACS和ACO的活性，明显抑制了肥城桃果实内源乙烯的生物合成。NO和外源乙烯共同处理的肥城桃果实内源乙烯生物合成低于外源乙烯单独处理而高于NO单独处理，表明NO对外源乙烯具有拮抗作用。【结论】NO抑制了果实内源乙烯的生物合成，且抑制了外源乙烯对果实乙烯生物合成的催化作用。

Effects of Nitric Oxide and Exogenous Ethylene Treatments on Ethylene Biosynthesis in Feicheng Peach

【OBJECTIVE】The effects of nitric oxide (NO) and exogenous ethylene on ethylene biosynthesis in ‘Feicheng’ peaches were studied. The effect of NO on the physiological actions of exogenous ethylene was explored.【METHOD】‘Feicheng’ peaches were fumigated with 10 μl·L-1 NO, 1000 μl·L-1 ethylene, separately or 10 μl·L-1 NO and 1000 μl·L-1 ethylene. The changes of ethylene biosynthesis in ‘Feicheng’ peach fruit were studied【RESULTS】The exogenous ethylene promoted the biosynthesis of endogenous ethylene in peach fruit. The treatment with NO reduced significantly the activities of ACS and ACO, and inhibited remarkably the biosynthesis of ethylene in fruit. The ethylene biosynthesis in fruit treated with NO and exogenous ethylene was lower than treatment with exogenous ethylene, but higher than the treatment with NO. This suggested that NO inhibited significantly the physiological actions of ethylene. NO could react directly with the metal center of ethylene receptor, change the electron cloud density and the spatial structure of ethylene receptor, and prevent the binding of exogenous ethylene to receptor. NO could also deoxidize the Cu2＋, the cofactor of ethylene receptor, to Cu＋. Although exogenous ethylene could bind with receptor, Cu＋ could not activate the receptor. As a result, ethylene could not exert its physiological effects.【CONCLUSION】NO could inhibit the biosynthesis and physiological effects of ethylene, and retard the physiological actions of exogenous ethylene.