Relationship Between Stimulated Ethylene Production and Alternative Respiration Pathway in “Royal Gala” Apple Fruit

Endogenous ethylene production and alternative oxidase (AOX) protein expression in "Royal Gala" apple fruits were investigated after treatments with cold (0℃ for 1 week) and heat (38℃ for 1 h).A monoclonal antibody to the terminal oxidase of the alternative pathway from Sauromatum guttatum was used to identify the AOX protein in apple fruits.The molecular mass of AOX in "Royal Gala" apple fruits is approximately 38 kDa, similar to those reported in tobacco and tomato.The cold treatment depressed the release of endogenous ethylene production before the climacteric ethylene production and obviously induced the expression of AOX protein expression.The heat treatment had the opposite effects on the ethylene production and AOX protein expression.In addition, the climax of endogenous ethylene production preceded the maximum AOX expression after the cold temperature treatment.It is therefore proposed that in climacteric fruits the production of induced ethylene is not coordinated with the level of AOX protein.