Effects of exogenous adenosine triphosphate and 2,4- dinitrophenol on membrane stability and chilling injury of harvested 'Kim Ju' guava fruit

Abstract

Depletion of cellular energy and loss of membrane stability contribute to chilling injury (CI) in horticultural crops stored below 13°C. In this study, the effects of exogenous ATP and 2,4-dinitrophenol (DNP; ATP production inhibitor) on membrane stability and chilling injury of guava fruit were investigated. Mature 'Kim Ju' guava fruit were dipped in distilled water (control); 0.5, 1 and 2 mM of ATP; 0.5, 1 and 2 mM of DNP for 30 min, and stored at 8°C for 14 d. It was shown that cellular energy (ATP content and energy charge (EC)) decreased during cold storage. This reduction coincided with the increases in membrane damage (percentage of electrolyte leakage (EL) and malondialdehyde (MDA) content) and CI index as well as a decrease in membrane transport enzyme (H+-ATPase and Ca2+-ATPase) activities. The fruit treated with 1 mM ATP had markedly higher levels of cellular energy and ATPase activity than the control within the first 14 days. Moreover, the membrane damage and CI index were significantly lower than the control after 10 days. In contrast, treatment with 1 mM DNP exhibited opposite results by reducing cellular energy and ATPase activity and increasing membrane damage and CI index comparing with ATP treatment. These results suggest that chilling injury development of guava fruit associated with a decrease in energy level and loss of membrane stability. Exogenously applied ATP could inhibit chilling injury by improving cellular energy and membrane stability whereas insufficient energy by applied DNP accelerates chilling injury due to the loss of membrane stability.