ACCUMULATION OF γ-AMINOBUTYRIC ACID IN APPLE, STRAWBERRY AND TOMATO FRUIT IN RESPONSE TO POSTHARVEST TREATMENTS

Abstract

γ-Aminobutyric acid (GABA) concentrations have been investigated in apple and strawberry fruit exposed to elevated CO 2 levels, and in tomato fruit of S. pennellii introgression lines in cultivated tomato (S. lycopersicum) stored at 3°C. In apple fruit, external CO 2 injury was much greater in fruit exposed to 2.5 and 5% CO 2 than at 1% CO 2 , and injury was enhanced by 1-methylcyclopropene (1-MCP) and inhibited by diphenylamine (DPA) treatment before exposure to 5% CO 2 . GABA accumulated in fruit skin to a greater extent when exposed to 2.5 and 5% CO 2 than to 1% CO 2 , while 1-MCP treated fruit had enhanced GABA accumulation and DPA treated fruit less GABA accumulation compared with 5% CO 2 alone. Strawberries contained undetectable amounts of GABA at harvest, but its concentration increased markedly during storage in 20% CO 2 . Tomato fruits of L. pennellii introgression lines stored at 3°C for 3 weeks showed elevated GABA concentrations, and the % increase over GABA concentrations at harvest was greater in fruit of introgression lines with higher susceptibility to chilling injury. Overall, the results suggest that GABA accumulations may be related to postharvest stresses in fruit, but further research is required to understand the relationships.