Evidences suggest that specific patterns of histone posttranslational modifications (PTMs) and their crosstalk could determine transcriptional outcomes in plant upon abiotic stress. However, the detail molecular mechanisms of these histone PTMs remain largely unknown. We studied dynamic response of global histone N-ternimal acetylations and phosphorylation to salinity stress and found that three adjacent PTMs sites in histone 3 (H3) (including K9, S10 and K14) altered significantly upon salinity treatments. Amongst them, the level of H3 lysine 14 acetylation (H3K14Ac) and H3 Serine 10 phosphorylation (H3S10Phos) increased while the level of H3 lysine 9 acetylation (H3K9Ac) decreased respectively. Chromatin immuno-precipitation (ChIP) experiments demonstrated that H3K9Ac and H3K14Ac could be found in the promoter region of a gene GmGST (codes for glutathione S-transferase), while H3S10Phos was found mostly at the down-stream of the GmGST coding region. GST plays a crucial role in the glutathione-ascorbate cycle which could eliminate the salinity stress induced reactive oxygen species. Furthermore, our preliminary proteomic data indicated that, the abundance of GST and other two other enzymes ascorbate peroxidase (APX) and GSH-dependent dehydroascorbate reductase (DHAR) that involved in the this cycle were observed up-regulation. Besides, 28 other up-regulated proteins were found to be associated with redox regulation or ROS signaling. In addition, histone PTM-peptide based pull down experiments demonstrated that H3S10Phos peptide could be specifically recognized by APX. It implies that the over-accumulated APX could feedback to the GST expression system.
Our findings may provide us a better understanding of the soybean adaptation mechanism upon salinity stress.