Differential proteomic analysis of dwarf characteristics in cucumber (Cucumis sativus Linn.) stems

Dwarfism was one of the most important agronomic traits in cucumber breeding. The current study was conducted to identify dwarf-related proteins using two-dimensional electrophoresis. Twenty-two differentially expressed protein spots were detected between dwarf and vine genotypes while 20 of them were successfully identified by MALDI-TOF/TOF MS. Out of 20 identified proteins in dwarf genotype, 14 were up-regulated and six were down-regulated. The classification of differential proteins showed that the identified proteins were functionally involved in photosynthesis, energy metabolism, cytoskeletal functions, transduction and signal regulation, detoxification and redox regulation. Five differentially regulated proteins were analyzed using the technique quantitative real-time PCR (qRT-PCR). The results showed that four proteins, including histone deacetylase, the EIN2-like protein, chlorophyll A/B binding protein, and ubiquitin-conjugating enzyme Spm2 (E2) were up-regulated and one F-box family protein was down-regulated in the dwarf genotype. Further western blot analysis revealed that only E2 protein was detected in the dwarf genotype, indicating its important role in the cucumber dwarf trait.