The effects of histone acetylation on the maize allele PL1-blotched

Abstract

Covalent modifications of DNA and nucleosomal histone proteins associated with eukaryotic chromatin have the potential to alter expression of a gene without change in its DNA sequence. One gene regulated through this so-called epigenetic process is the Pl1- Blotched gene of maize. Pl1-Blotched is a allele of the purple1 (pl1) gene, which encodes a transcription factor that activates synthesis of purple anthocyanin pigments. Pl1-Blotched is unusual in that it leads to variegated, rather than uniform, pigmentation. At the molecular level, this phenotype is associated with low expression of pl1 mRNA, a novel pattern of DNA methylation and condensed chromatin structure. To ask if acetylation of nucleosomal histone proteins might be involved in regulating the chromatin organization of Pl1-Blotched, this allele was crossed into 40 lines containing transgenes that target reduction of various histone acetyltransferase and histone deacetylase genes. Some of the lines led to altered Pl1-Blotched pigmentation. Detailed analysis of molecular changes underlying the altered pigmentation resulted in models that implicate both histone acetyltransferase and histone deacetylase genes in controlling expression of Pl1-Blotched. These findings lay the foundation for future studies aimed at further understanding the interplay between histone modification and regulation of gene expression.