Histone variants and acetylated species from the alfalfa plant Medicago sativa

The histones from the alfalfa plant Medicago sativa have been characterized in terms of type variants and levels of acetylation. Histones were isolated directly from total plant tissue (callus), eliminating the need to develop methods for nuclear isolation. An acid-urea-polyacrylamide gel with a transverse Triton X-100 gradient resolved and identified in a single gel at least one type of histone H4, two variant forms of histone H2B, two variant forms of histone H3, and four variant forms of histone H2A from a crude histone preparation. Histone H4 was present 25% in an unmodified state and 75% as monomodified, presumably as monoacetylated histone. Both histone H3 variants displayed five bands, consistent with up to four internal sites of acetylation. The two H3 variants differed in their steady-state level of acetylation, suggesting that they may reside in different chromatin environments. Several histone H1 species were identified by solubility and cross-reactivity with antiserum raised against the globular part of bovine H1 °, indicating conservation of epitopes between histone H1 of mammals and higher plants.