Feasibility study of a tissue-specific approach to barley proteome analysis: aleurone layer, endosperm, embryo and single seeds

Proteome analysis in the pI 4-7 range of aqueous extracts from whole barley seeds results in complex 2D-gel spot patterns that represent proteins from all seed tissues. Proteins were extracted from dissected aleurone layer, embryo and endosperm for separate analysis of these components and comparison with single seed extracts. The analysis showed that while the starchy endosperm comprises approximately 85% of the mature seed dry weight, it contributes less than 50% of the soluble protein to seed extracts. Although the aleurone layer and embryo are minor components of the seed in terms of dry weight, their proteins contribute significantly to the 2D-gel pattern. Distinct but overlapping patterns were observed for the dissected tissues. While whole seed gels contained about 850 spots, endosperm, aleurone layer and embryo gels had about 575, 850 and 1000 spots, respectively, representing a total increase of at least 15%. Protein patterns were also reduced in complexity and this enrichment of subsets of proteins facilitated identification by mass spectrometry of proteins of interest in mature seed tissues and developing endosperm. These techniques can therefore be used with advantage to describe the proteomes of dissected seed tissues. (C) 2003 Elsevier Ltd. All rights reserved.