Comparative Analysis of the Protein Profile from Biofortified Cultivars of Quality Protein Maize and Conventional Maize by Gel-Based and Gel-Free Proteomic Approaches

Biofortification of crops has promoted the development of quality protein maize (QPM), which are rich in essential amino acids. However, the proteomic rebalancing of QPM cultivars grown in Brazil remains unknown. Here, we show the compositional equivalence and protein profiles from two QPM cultivars (BR-473 and BR-451, named here as QPM1 and QPM2, respectively) compared to a commercial non-QPM hybrid (BRS-4103, non-QPM), by using complementary 2-DE-based (gel-based) and bottom-up shotgun (gel-free) proteomic approaches. The compositional equivalence observed in these cultivars was expected for Zea mays. Among differentially expressed proteins (DEPs) identified, storage proteins as non-zeins were generally up-regulated, where zeins were down-regulated in QPM cultivars. In turn, defense and cell stress proteins as heat shock protein (HSP) and ribosome-inactivating protein (RIP) were down-regulated. Together, these findings point the superior nutritional value of proteins from QPM cultivars as well as their susceptibility to pathogens.