Top-down mass spectrometry of histone modifications in sorghum reveals potential epigenetic markers for drought acclimation

•A top-down mass spectrometry workflow for profiling sorghum histone was presented.•Histone modifications in sorghum under different watering conditions were studied.•An unusual pyruvic acid modification was putatively identified on H2A proteoforms.•Terminal clippings of several histones changed significantly among samples.•Potential epigenetic factors for drought acclimation in sorghum were discovered.