The objectives of this study were to understand the role of ethylene and nutrients (Ca 2+ , Mg 2+ , K + and N) on bitter pit (BP) development in wild type (GS) and ethylene suppressed (68G and 103Y) 'Greensleeves' apples. The transgenic line 68G is suppressed for 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) and line 103Y is suppressed for ACC synthase (ACS). Suppression of ethylene biosynthesis reduced BP incidence and severity. Lower ethylene biosynthesis, in ethylene-suppressed

more »

... notypes, had no effect on Ca 2+ , Mg 2+ , K + and N concentrations in fruit cortical tissue. In all genotypes, fruit with BP had lower Ca 2+ and higher Mg 2+ concentrations and higher Mg 2+ /Ca 2+ ratio in cortical tissue. The results indicate that high levels of ethylene biosynthesis and Mg 2+ in cortical tissue can enhance fruit susceptibility to BP incidence.