Mass Spectrometry-Based Characterization of Histone Post-Translational Modifications in Sugarcane

Histones, the core components of nucleosomes, play an important role in chromatin structure and function through post-translational modifications (PTMs) that regulate gene expression without altering the DNA sequence. Sugarcane (Saccharum spp.), a highly polyploid and economically significant crop, has a complex genome with a limited understanding of histone PTMs. In this study, we employed mass spectrometry to characterise the PTMs of histones in internodes of field-grown commercial sugarcane, harvested at different times of the day, with a focus on histones H2A and H2B, which had not been previously studied in this context. Using a sorghum histone catalog as a reference, we identified 26 H1, 91 H2A, 70 H2B, 5 CENH3, 36 H3.1, 23 H3.3, 18 H3.3L, and 57 H4 loci in the sugarcane genome. We detected extensive PTMs, including acetylation and methylation, across histones H2A, H2B, H3, and H4. Canonical and variant histones showed distinct post-translational modification (PTM) patterns, highlighting their functional specialisation. This study provides a comprehensive catalog of sugarcane histone PTMs, offering insights into their roles in chromatin dynamics and gene regulation, with potential applications in crop improvement and stress adaptation.