Abstract
Flooding injury is one of the major constraints for cultivation of soybean. A proteomic approach was used to clarify mechanisms of the flooding injury. Two-day-old seedlings were flooded for 1 day, and proteins were extracted from root tips of the seedlings. Comparative analyses on quantity and phosphorylation states of proteins between untreated and flooded samples were performed. For quantitative analysis, tryptic peptides were analyzed using mass spectrometry. For phosphoproteomics, phospho-proteins and -peptides were enriched using phosphoprotein purification column and titanium oxide beads, respectively, and were analyzed using mass spectrometry. As results, proteins related to energy generation and signalling were increased, and protein modification and cell structure were decreased by flooding. Alternatively, phosphoproteomics showed that proteins related to energy generation, cell structure, protein modification and transcription were dephosphorylated, and primary metabolism, protein degradation and translation were phosphorylated by flooding. It is suggested that response to flooding stress is regulated by modulation of protein quantities and protein phosphorylations.
