Comparative proteomics analysis of Brassica napus in response to drought stress

Drought is one of the most severe stresses leading to retardation of plant growth and development and loss of crop yield. Here we examined the proteome changes of an important oil seed crop canola Brassica napus under drought stress over a 14 day period. Using iTRAQ LC-MS/MS, we identified 2,244 proteins expressed during drought stress. Among them, 412 proteins showed significant changes in abundance under stress, and 67, 243, 287, and 79 proteins were differentially expressed in 3rd, 7th, 10th, and 14th day of drought stress, respectively. Functional analysis of the 412 proteins indicated that the number of proteins associated with “Metabolism”, “Protein synthesis”, and “Signaling” decreased, while those related to “Photosynthesis” and “Stress and defense” increased in response to drought stress. In particular, the proteome profiles at the 7th and 10th day were similar to each other, although there were much more post-translational modifications (PTM) at the 10th day of drought. Interestingly, 286 of 2,244 proteins exhibited PTMs in response to drought stress, 82 of which were differentially changed in drought-stressed plants, and 60 were observed at the 10th day. Furthermore, comparison of protein expression changes with those of gene transcription showed that there was positive correlation in B. napus, although there were different patterns between transcripts and proteins at each time point. As drought stress prolongs, most of the protein abundance changes may be attributed to gene transcription, and PTMs clearly contribute to the protein diversity and functions.