MeJA induces chilling tolerance in loquat fruit by regulating proline and γ-aminobutyric acid contents

Loquat fruit were pretreated with 10 mu mol l(-1) methyl jasmonate (MeJA) for 24 h at 20 degrees C and then stored at 1 degrees C for 35 days to investigate the effect of MeJA treatment on chilling injury (Cl) and changes in the contents of proline and gamma-aminobutyric acid (GABA). The control fruit exhibited severe flesh leatheriness, a specific Cl symptom, after 21 days of storage at 1 C, but it was reduced in MeJA-treated fruit. During the development of CI in fruit, proline and GABA accumulated with the storage time, while MeJA treatment enhanced the increases in proline and GABA contents. The MeJA-treated fruit exhibited higher activities of Delta(1)-pyrroline-5-carboxylate synthetase (P5CS), ornithine delta-aminotransferase (OAT) and glutamate decarboxylase (GAD), and lower proline dehydrogenase (PDH) activity than control during storage. These results suggest that the reduction in Cl in loquat fruit by MeJA may be due to the increased proline and GABA contents. (C) 2012 Elsevier Ltd. All rights reserved.