No abstract

No abstract

No abstract

No abstract

No abstract

α- and β-galactosidase (α- and β-Gal) activities, firmness and pigment content were analysed in tomato (Lycopersicon esculentum Mill.) pericarp during fruit growth and ripening, comparing normal fruit with transgenic fruit containing an ACC-synthase antisense transgene. Normal and transgenic immature green fruit had similar temporal patterns of total α- and β-Gal activity. Immature 21-day-old fruit displayed 93% and 134% higher α- and β-Gal activity on a per gram fresh weight basis, respectively, than mature-green fruit. During ripening, normal fruit presented increasing levels of α- and β-Gal activity towards the red-ripe stage. β-Gal II was detected in mature-green tomatoes; it rose rapidly and reached maximum values at the red-ripe stage. In contrast, α- and β-Gal activity in antisense fruit decreased after reaching the breaker stage, and a low continuous level of activity was apparent between 54 and 108 days after anthesis. 48- to 108-day-old transgenic fruit showed constant basal levels of β-Gal II. There were no significant differences in enzyme activity between antisense attached and detached fruit. An exogenous ethylene treatment performed in transgenic tomatoes brought about a promotive effect on total α- and β-Gal activity in general and on β-Gal II in particular, thus suggesting a role for ethylene in de novo synthesis or activation of these enzymes. Softening, chlorophyll breakdown and lycopene biosynthesis were impaired in the antisense fruits, but the impairment was only complete for lycopene synthesis and all were reversed by applied ethylene. These results can be associated with the signal transduction pathways proposed to be operational during tomato ripening.

No abstract

The potential use of 1-methylcyclopropene (1-MCP) alone or as a supplement to cold storage to delay the softening of 'Brown Turkey' figs (Ficus carica L.) was studied. Figs were treated with 0, 0.25, 0.5 or 5 µl l −1 1-MCP at 25 • C for 8 h and stored at 20 • C until evaluated. Figs treated with 0.5 or 5 µl l −1 1-MCP had higher ethylene production and respiration rates but slower softening than untreated fruit and those treated with 0.25 µl l −1 1-MCP. Early-harvested firm figs and late-harvested soft figs were untreated or treated with 0.5 or 5 µl l −1 1-MCP at 25 • C and stored at 0 • C for 19 days. Firm figs treated with 1-MCP showed an early peak in ethylene synthesis, higher respiration rate and were firmer than control fruit. In contrast, soft figs did not respond to 1-MCP except for a late increase in respiration rates of fruit treated with 5 µl l −1 1-MCP. 1-MCP appeared to have a relatively limited effect on slowing ripening of 'Brown Turkey' figs and its effect was influenced by ripening stage.