Identification of nuclear proteins in soybean under flooding stress using proteomic technique.

Flooding stress restricts soybean growth, it results in decrease the production. In this report, to understand how nuclear proteins in soybean affected by flooding, abundance changes of those proteins was analyzed. Nuclear proteins were extracted from the root tips of soybean treated with or without flooding stress. The extracted proteins were analyzed using a label-free quantitative proteomic technique. Of a total of 94 nuclear proteins that were found to be responsive to flooding, the 19 and 75 proteins were increased and decreased, respectively. The identified flooding-responsive proteins were functionally classified, revealing that 8 increased proteins changed in protein synthesis, posttranslational modification, and protein degradation, while 34 decreased proteins were involved in transcription, RNA processing, DNA synthesis, and chromatin structure maintenance. Among these proteins, those whose levels changed more than 10 fold included two poly ADP-ribose polymerases and a novel G-domain-containing protein that might be involved in RNA binding. The mRNA expression levels of these three proteins indicated a similar tendency to their protein abundance changes. These results suggest that acceleration of protein poly-ADP-ribosylation and suppression of RNA metabolism may be involved in root tip of soybean under flooding stress.