Abstract:The objective of this work was to investigate the changes of differential expressed proteins in response to sunburn stress on loquat pericarp. The fruits of loquat cultivar ‘Jinzhong’ and ‘Honghouben’ sunburned for 90 min at 40 ℃ during color changing period were selected as experiment materials, among which the ‘Jinzhong’ loquat is poorer than ‘Honghouben’ at sunburn resistance. Total proteins in pericarp were separated using twodimensional electrophoresis and differentially expressed proteins were identified using matrixassisted laser desorption ionization timeofflight/timeofflight mass spectrometry (MALDITOF/TOFMS). (1) Total 64 proteins were changed at least 2fold differences in abundance, among which 56 proteins were successfully identified with 38 in ‘Jinzhong’ and 23 in ‘Honghouben’. (2) These identified proteins were involved in stress response and defense (accounting for 30.3%), photosynthesis(14.3%), respiration (25.0%), protein metabolism(14.3%)and some other physiological processes. (3) Compared to ‘Honghouben’, the abundance of many heat shock protein (HSP) was increased, and the abundance of proteins participating in respiration was also increased in order to generate more energy in ‘Jinzhong’. But the contents of many proteins related to photosynthesis as well as ascorbic acid peroxidase (APX) and polyphenol oxidase (PPO) removing reactive oxygen species (ROS) were all decreased, otherwise the activity of PPO was declined in ‘Jinzhong’. It is suggested that in order to enhance sunburn resistance in loquat, the content and activity of the enzymes removing ROS may be increased, the amount of HSP may need to some extent, and respiration and photosynthesis might be kept at the normal level.