Comparmentation of Amino Acids in Tomato Fruit Pericarp Tissue

Abstract

During ripening of tomato fruit, there is a progressive decline in labeled amino acid incorporation into proteins of pericarp tissue (3). The specific radioactivity of ethylene produced from [¹⁴C]-methionine is also lower in ripe tissue than in green tissue and ethylene production in ripe tissue is relatively insensitive to aminoethoxyvinylglycine (AVG) (2). Also, the rate of ethylene production by tomato pericarp tissues is, under certain conditions, less than would be expected on the basis of ACC content (7). These phenomena could be due to changing uptake or compartmentation patterns of amino acids as the fruit ripens. A decompartmentalized methionine pool might dilute added labeled methionine resulting in lower incorporation of label into proteins and ethylene. A knowledge of amino acid uptake and compartmentation characteristics in tissue at various stages of ripening is important in understanding these observations, and the regulation of 1-aminocyclopropane-1 carboxylate (ACC) production and conversion to ethylene in tomato fruit.