Proteomic analysis of the heat stress response in leaves of two contrasting chrysanthemum varieties

High temperature stress causes damages to chrysanthemum by adversely affecting its growth and development. To identify differentially expressed proteins under heat stress, heat-tolerant variety (Chrysanthemum nankingense ) and heat-susceptible variety (Chrysanthemum ‘Wanfen’) were selected to contrast the full leaf proteome profiles with or without 6 h of heat stress (40°C), a parameter established in our previous study. Isobaric tags for relative and absolute quantitation (iTRAQ) was used in combination with tandem mass spectrometry and multidimensional liquid chromatography technology. Results of physiological tests showed that the variation of relative ion leakage and malondialdehyde were larger in Chrysanthemum ‘Wanfen’ than those in Chrysanthemum nankingense. In proteomics experiments, 250 proteins were identified, of which 43 were differentially expressed. Functional classification indicated that most of proteins were involved in photosynthesis, metabolic processes, oxidation-reduction processes and transport. Furthermore, 12 differentially expressed proteins were analyzed at the mRNA level under different durations (0 h, 3 h and 6 h) of heat treatment by qRT-PCR. The results showed that under heat stress the expression patterns of the rest 11 genes coding the altered proteins were correspondent to their respective protein levels with the exception of actin.