Abstract
Ethylene plays an important role in the initiation and continuation of ripening in climacteric fruits. Analyses of ethylene perception have shown that ethylene receptors negatively regulate the ethylene response. To elucidate the role of ethylene receptors during apple ripening and storage, we isolated cDNAs of three putative ethylene receptor genes Md-ETR1, Md-ERS1 and Md-ERS2, and examined their expression patterns in two apple varieties, 'Orin' and 'Fuji', which have distinct characteristics in ethylene production and storage life. Although Md-ETR1 appeared to be constitutively expressed in fruits, Md-ERS1 and Md-ERS2 were expressed only at the climacteric fruit stage. Expression of these receptor genes were suppressed by treatment with a inhibitor of ethylene action, 1-methylcyclopropene. Ethylene receptor mRNAs accumulated more abundantly in 'Fuji', which has long storage life, than in 'Orin'. This result supports the model that ethylene receptors negatively regulate the ethylene response in apple.
