Proteomic analysis of plumules and coleoptiles in maize between hybrids and their corresponding inbred lines

The plumule and coleoptile influence the emergence and vigor of the seedling and demonstrate distinct heterosis during maize (Zea mays L.) development. Comparative two-dimensional analysis was performed on plumules and coleoptiles from 3.5 days-cultivated seedlings of five widely used hybrids in China and their corresponding parental lines to dissect the genetic mechanism of heterosis. Compared to their parental lines, 64 % (2,127/3,310) of the differentially expressed proteins were nonadditively accumulated in the five hybrids. Up-regulated above the high parent, a similar expression pattern in all five tested hybrids, was the major expression pattern accounting for 68 % (1,446/2,127) nonadditive proteins. Forty-two nonadditive protein spots with significant differences between the hybrids and their parental lines were analyzed by mass spectra. Homology searches separated them into six groups with two abundant functional classes of cell detoxification (33 %) and metabolism (26 %), implying their importance for heterotic manifestation of the different hybrids at 3.5 days-cultivated seedling stage. The differential accumulation and expression of herbicide safener protein 1 in cell detoxification implied that exploration of the molecular mechanism of heterosis should be studied in a systematic network. Four potential functional polymorphisms were identified in SBP1 gene providing possible interpretation for the differential expression of SBP1 at transcriptional and translational levels.