Nonadditive Protein Accumulation Patterns in Maize (Zea mays L) Hybrids during Embryo Development

Heterosis describes the superior performance of heterozygous F-1-hybrid plants compared to their homozygous parental inbred lines-In the present-study heterosis-was detected for length, weight and the time point of seminal root primordia initiation in maize (Zea mays L) embryos of the reciprocal H-1-hybrids UH005xUH250 and UH250xUH005 A two-dimensional gel electrophoresis (2-DE) proteome survey of the most abundant proteins of the reciprocal hybrids and their parental inbred lines 25 and 35 days after pollination revealed that 141 of 597 detected proteins (24%) exhibited nonadditive accumulation in at least one hybrid Approximately 44% of all nonadditively accumulated proteins displayed an expression pattern that was not distinguishable from the low parent value Electrospray ionization-tandem mass spectrometry (ESI-MS/MS) analyses and subsequent functional classification of the 141 proteins revealed that development, protein metabolism, redox-regulation glycolysis, and amino acid metabolism were the most prominent functional classes among nonadditively accumulated proteins In 35-day-old embryos of the hybrid UH250xUH005, a significant up-regulation of enzymes related to glucose metabolism which often exceeded the best parent values was observed A comparison of nonadditive protein accumulation between rice and maize embryo data sets revealed a significant overlap of nonadditively accumulated proteins suggesting conserved organ- or tissue-specific regulatory mechanisms in monocots related to heterosis