Amelioration of chilling stress by arginine in tomato fruit: Changes in endogenous arginine catabolism

Freshly harvested tomato fruit were pretreated with 0.2 mM arginine at -35 kPa for 0.5 min and then stored at 2 degrees C for 28 d to investigate the effect of exogenous arginine treatment on endogenous arginine catabolism in relation to chilling injury (CI). Arginine treatment reduced the CI index of fruit and enhanced accumulation of polyamines, especially putrescine, and praline, which resulted from the increased activities of the catabolic enzymes arginase, arginine decarboxylase, ornithine decarboxylase and ornithine delta-aminotransferase at most sampling times. Nitric oxide synthase activity was also increased by arginine treatment, which at least partly contributed to the increased nitric oxide concentration. These results revealed that the reduction in CI by exogenous arginine may be due to the accumulation of putrescine, praline and nitric oxide induced by activating the different pathways of endogenous arginine catabolism. (C) 2012 Elsevier B.V. All rights reserved.