Proteomic identification of toxic volatile organic compound-responsive proteins in Arabidopsis thaliana

The proteins that are responsive to toxic volatile organic compounds (VOC) such as formaldehyde and toluene were analyzed with proteome analysis using two-dimensional difference image gel electrophoresis (DIGE) technology. Twenty-one days after germination (DAG) seedlings of Arabidopsis thaliana were exposed either to the gaseous formaldehyde or toluene in an airtight box installed in a plant growth chamber maintained at 24 degrees C under the long day condition with relatively low light condition. Comparative expression analysis revealed 14 and 22 protein spots as proteins displaying at least 1.5-fold differences in expression upon formaldehyde and toluene treatment, respectively, compared to those of untreated control. Most of the isolated spots were successfully identified by peptide analysis using LC-MS-MS. The VOC-responsive proteins contain ATP synthase CF1, ribulose-1,5-bisphosphate carboxylase/oxygenase, photosystem II light harvesting complex, and enolase, which are components of photosynthesis and carbohydrate metabolism. Despite the relatively low light intensity was applied, many identified VOC-induced proteins were previously known to be up-regulated upon high light stimulus. In addition, proteins involved in the toxin catabolic process and stress hormone-related proteins were identified as toluene-induced proteins. Although the exact function of most of the VOC-responsive proteins identified in these experiments had not been characterized, the protein expression analysis using DIGE was clearly demonstrated that plants are capable of responding actively to VOCs at translational level, and identified proteins may provide valuable tools to account for the effects of abiotic stress caused by air pollutants such as VOCs in plant.