Changes of polyamines and CBFs expressions of two Hami melon (Cucumis melo L.) cultivars during low temperature storage

Hami melon (Cucumis melo L. var. inodorus Jacq) is susceptible to chilling injury (CI) during low temperature storage, which causes changes in physiological mechanisms and gene expression. In this study, cold tolerance of two Hami melon cultivars, namely Xinmi No. 3 and Xinmi No. 11 was evaluated. We assessed changes of membrane permeability, the content of polyamines (PM), and the expression of C-repeat/dehydration-responsive element (CRT/DRE)-binding factors (CBFs) in different section of fruit of each cultivar stored at 3 C under 7540% relative humidity. The results showed that Xinmi No. 11 was more cold tolerant than Xinmi No. 3, the content of PM and the expression of CmCBFs in the cold-tolerant cultivar were significantly higher than in the cold-sensitive cultivar during storage at 3 C. CI was observed in the peel tissue, but not in the pulp tissue. The content of PM and the expression of CmCBFs in the peel tissue were significantly higher than in the pulp tissue. The membrane permeability, putrescine (Put), spermine(Spm), and the expression of CmCBF1 and CmCBF3 in the peel tissue of Hami melon fruit increased with the degree of CI. Our results provide novel evidence about the positive correlation between the content of PM, the expression of CmCBF1 and CmCBF3 and cold tolerance. The CI had major impact on Put, Spm and membrane permeability. The assessed parameters could provide sensitive indicators reflecting cultivar cold tolerance of Hami melon fruit under chilling stress.