Activity and Gene Expression of Ethylene Biosynthetic Enzymes of 'Irwin' Mango during Fruit Ripening

The present investigation was undertaken to study the effect of storage temperature in controlling ethylene production through the activity and gene expression of ethylene biosynthetic enzymes of 'Irwin' mango during fruit storage. Ethylene evolution and activities of ethylene biosynthetic enzymes, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase were investigated using fruit harvested at commercial maturity and stored at 20 and 13 degrees C, together with gene expression of these enzymes. Just after harvest respiration was high although it soon decreased. A climacteric peak was observed after 6 days at 20 degrees C or 8 days at 13 degrees C. Peak ethylene evolution occurred after 2 days at 20 degrees C or 12 days at 13 degrees C although ethylene evolution steadily increased after 4 days at 13 degrees C. Highest activities of ACC synthase and ACC oxidase were recorded after 2 at 20 degrees C and 8 days at 13 degrees C, coinciding with ethylene climacteric peaks. Expression of both ACC synthase and ACC oxidase genes was higher for fruit stored at 13 degrees C than at 20 degrees C. The dynamism of ethylene biosynthetic enzyme activity and gene expression of those enzymes indicated enhanced effectiveness at lower storage temperatures.