Proteomic analysis of early germs with high-oil and normal inbred lines in maize

High-oil maize as a product of long-term selection provides a unique resource for functional genomics. In this study, the abundant soluble proteins of early developing germs from high-oil and normal lines of maize were compared using two-dimensional gel electrophoresis (2-DGE) in combination with mass spectrometry (MS). More than 1100 protein spots were detected on electrophoresis maps of both high-oil and normal lines by using silver staining method. A total of 83 protein spots showed significant differential expression (>two-fold change; t-test: P < 0.05) between high-oil and normal inbred lines. Twenty-seven protein spots including 25 non-redundant proteins were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Functional categorization of these proteins was carbohydrate metabolism, cytoskeleton, protein metabolism, stress response, and lipid metabolism. Three such proteins involved in lipid metabolism, namely putative enoyl-ACP reductase (ENR), putative stearoyl-ACP desaturase (SAD) and putative acetyl-CoA C-acyltransferase (ACA), had more abundant expressions in high-oil lines than in normal. At the mRNA expression level, SAD, ENR and ACA were expressed at significantly higher levels in high-oil lines than in normal. The results demonstrated that high expressions of SAD, ENR and ACA might be associated to increasing oil concentration in high-oil maize. This study represents the first proteomic analysis of high-oil maize and contributes to a better understanding of the molecular basis of oil accumulation in high-oil maize.