Abstract: 【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.

Key words: Biosynthesis, Receptor, Peach (Prunus persica), Ethylene, Nitric oxide