Cereal proteins have formed the basis of human diet worldwide, and their level of consumption is expected to increase. The knowledge of the protein composition and variation of the cereal grains is helpful for characterizing cereal varieties and to identify biomarkers for tolerance mechanisms. Grains produce a wide array of proteins, differing under conditions. Quantitative proteomics is a powerful approach allowing the identification of proteins expressed under defined conditions that may contribute understanding the complex biological systems of grains. Isobaric tags for relative and absolute quantitation (iTRAQ) is a mass spectrometry-based quantitative approach allowing, simultaneously, for protein identification and quantification from multiple samples with high coverage. One of the challenges in identifying grains proteins is their relatively high content (~90-95%) of carbohydrate (starch) and low protein (~4-10%) and lipid (~1%) fractions. In this chapter, we present a robust workflow to carry out iTRAQ quantification of the starchy rice grains.
Keywords: Chalkiness; Isobaric tags for relative and absolute quantification (iTRAQ); Oryza sativa; Protein biomarkers; Seed proteomics.