Profiling of differentially expressed proteins in mature kernels of Korean waxy corn cultivars using proteomic analysis

Maize (Zea mays L.) is the most important crop such as food for humans and feed for animals. Although new varieties of maize have been extensively developed in Korea, little is known about differences in the proteomes of mature kernels among maize varieties. Three Korean waxy corn cultivars (Ilmichal, Eolrukchal 1, and Heukjinjuchal) have previously been developed. The total protein content is higher in Ilmichal than in Eolrukchal 1 or Heukjinjuchal, while the starch and fatty acid contents are similar among these three Korean waxy corns. To uncover the differences in proteomic profiles among these three Korean waxy corns, we performed proteomic analysis and compared their protein compositions. We detected 37 differentially expressed protein spots and identified the proteins using MALDI-TOF mass spectrometry. Of these proteins, 37.8 % were identified as storage proteins, 18.9 % as stress-related proteins, and 18.9 % as metabolism-related proteins. Storage proteins (globulin-2) and stress-related proteins (heat shock proteins and general stress proteins) were highly expressed in Ilmichal or Heukjinjuchal. Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis of corresponding genes of five randomly selected proteins, including glyoxalase family protein (accession number, B6SGF3), globulin-2 (Q7M1Z8), heat shock protein 1 and 3 (B6TGQ2 and B6TDB5), and vicilin-like embryo storage protein (Q03865), showed that the expression levels of the tested genes were well-correlated with protein abundance, suggesting that these proteins are also differentially regulated at the transcriptional level. Taken together, these results provide a better understanding of proteomic differences among Korean waxy corn cultivars and may support further molecular breeding efforts.