iTRAQ-based quantitative proteomic analysis of tea plant (Camellia sinensis (L.) O. Kuntze) during cold acclimation and de-acclimation procedures

To gain a better understanding on the mechanism of cold acclimation in tea plant [Camellia sinensis (L.) O. Kuntze] at the proteome level, an iTRAQ based quantitative proteome analysis was carried out to identify differentially accumulated proteins in the mature leaves which were collected at non-acclimated (NA), fully acclimated (CA) and de-acclimated (DA) stages. 407 and 477 proteins identified from CA and DA showed significant abundance changes (at 95% confidence) compared with NA, respectively. Moreover, 251 protein species changed their abundance in DA compared with CA. Those differential abundance protein species were mainly involved in metabolism, cell wall, photosynthesis, energy, protein synthesis, antioxidation, carbohydrate metabolic process and binding, and mapped to the pathways of biosynthesis of secondary metabolites, microbial metabolism in diverse environment, ribosome, metabolic pathway, sugar metabolism, protein processing, photosynthesis, and plant-pathogen interaction pathway. However, no significant correlation was detected between the identified proteins and cognate gene transcript levels by correlation analysis and qRT-PCR analysis. This study presents a comprehensive proteome in mature leaves at different cold acclimation status and provides new insights into cold acclimation mechanisms in tea plants.