Effect of Jasmonates Differed at Fruit Ripening Stages on 1-Aminocyclopropane-1-Carboxylate (ACC) Synthase and ACC Oxidase Gene Expression in Pears

Abstract

The effects of n -propyl dihydrojasmonate (PDJ), which is a jasmonic acid derivative, on 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase activities, their gene expressions, and ethylene productions in ‘La France’ pears ( Pyrus communis L.) were investigated. The fruit was harvested 156 days after full bloom, stored at 4 °C for 15 days, ripened at 20 °C, and then dipped into 0.39 m m PDJ solution at the preclimacteric stage (0 day of ripening at 20 °C) or the climacteric stage (9 days of ripening at 20 °C). In the skin of the PDJ-treated fruit at the preclimacteric stage, the expressions of ACC synthase ( ACS ) 1 and ACC oxidase ( ACO ) 1 were higher than the expressions of those in the untreated control. Ethylene production also increased in the PDJ-treated fruit. In contrast, the accumulation of the ACS1 messenger RNA (mRNA) levels in the skin and an increase of ethylene production were observed in the untreated control fruit at the climacteric stage, although the levels of mRNAs hybridized with ACO1 were not different between the PDJ-treated fruit and untreated control. The endogenous jasmonic acid levels in the skin increased in the PDJ-treated fruit regardless of the application times of PDJ. These results indicate that ACS1 may be an ACC synthase gene that is induced by jasmonates in pears, and that system 2 ethylene may be regulated by jasmonates.