Abstract
DNA methylation is important for regulating gene expression. The alteration of DNA methylation pattern affects gene expression and consequently may induce phenotypic alteration. When seeds of rice (Oryza sativa cv. Yamadanishiki) were exposed to 5-azadeoxycytidine, a methylation inhibitor, and cultivated to maturation, plants exhibited a typical dwarf phenotype with early heading. The traits and hypomethylation of genomic DNA was stably inherited over nine generations. Using this plant, we screened hypomethylated genomic regions by the methylation-sensitive amplified polymorphisms method, and identified several loci including Xa21-like. Xa21-like is a resistance gene against Xanthomonas oryzae, and progeny of the dwarf plants constitutively expressed Xa21-like and exhibited resistance to X. oryzae infection. The direct methylation mapping revealed that the promoter region of Xa21-like was totally demethylated in the dwarf progeny, while heavily methylated in the wild type. These results suggest that epigenetically acquired phenotype due to DNA methylation change is stably inherited over generations.
