Galactose Concentration and Metabolism in Pericarp Tissue from Normal and Non-ripening Tomato Fruit1

Abstract

Abstract Free galactose was detected in outer pericarp tissue from fruit of ‘Heinz 1350’ and nor tomato (Lycopersicon esculentum Mill.). The amount of free galactose increased almost 8-fold in ‘Heinz 1350’ fruit during ripening. In contrast, it did not change significantly in 32- to 52-day-old (post-pollination) nor fruit. A 25 μl drop of water ± 100 μg galactose was applied to the locular surface of 1.5 cm diameter pericarp disks. While disks from 40- and 60-day-old nor tomatoes, and from mature green and pink ‘Heinz 1350’ tomatoes, were able to reduce the level of free galactose to levels found in control tissue within 48 hr, disks of red ripe tissue were only able to metabolize 45% of the added galactose within this time. Pink ‘Heinz 1350’ tomatoe disks lost galactose more slowly than disks of mature green tomatoes. The results suggest that the increased amount of free galactose in pericarp tissue of ripening tomatoes may be the result of their progressive inability to metabolize galactose as they ripen.