Proteomic analysis of heterotic seed germination in maize using F1 hybrid DHM 117 and its parental inbreds

A number of differentially expressed proteins (DEPs) were identified in comparative two-dimensional gel electrophoresis analysis of dry and 24-h water-imbibed seeds of maize F₁ hybrid DHM 117 (BML 6 × BML 7) and its parental inbreds. Of the DEPs, 53.4% (86/161) in dry seeds and 58% (127/219) in water-imbibed seeds exhibited a nonadditive pattern in the F₁ hybrid as compared to parental inbreds. A total of 30 DEPs were categorized into different biological processes, most of which were related to metabolism and energy (34%), followed by storage proteins (27%), stress response (23%), transcription and translation (7%), cell cycle (3%), and hormone biosynthesis (3%). The transcript accumulation pattern of 8 selected genes corresponding to DEPs was examined using qRT-PCR. Interestingly, LEA protein Rab28 showed higher accumulation in dry seeds at both protein and transcript levels, whereas indole-3-acetaldehyde oxidase showed lower accumulation in water-imbibed seeds of the F₁ hybrid than the female parent at the protein level. Thus, the DEPs particularly involved in metabolic and energy processes, as well as hormone biosynthesis in the F₁ hybrid, might be responsible for heterotic seed germination in the F₁ hybrid. The DEPs identified in this study provide a scope for improving the seed germination trait of agricultural crops.