Histone hyperacetylation affects meiotic recombination and chromosome segregation in Arabidopsis.

In this study, the meiotic role of MEIOTIC CONTROL OF CROSSOVERS1 (MCC1), a GCN5-related histone N-acetyltransferase, is described in Arabidopsis. Analysis of the over-expression mutant obtained by enhancer activation tagging revealed that acetylation of histone H3 increased in male prophase I. MCC1 appeared to be required in meiosis for normal chiasma number and distribution and for chromosome segregation. Overall, elevated MCC1 did not affect crossover number per cell, but has a differential effect on individual chromosomes elevating COs for chromosome 4, in which there is also a shift in chiasma distribution, and reducing COs for chromosome 1 and 2. For the latter there is a loss of the obligate CO/chiasma in 8% of the male meiocytes. The meiotic defects led to abortion in about half of the male and female gametes in the mutant. In wild type, the treatment with trichostatin A, an inhibitor of histone deacetylases, phenocopies MCC1 over-expression in meiosis. Our results provide evidence that histone hyperacetylation has a significant impact on the plant meiosis.