摘要
Dear Editor,DECREASE IN DNA METHYLATION1 （DDM1） is a chromatin remodeling protein required for maintenance of cytosine and histone H3K9 methylation in heterochromatin regions in the genome of Arabidopsis thaliana （Gendrel et al., 2002）. A ddm 1 mutant also increases the rate of meiotic recombination in euchromatic but not heterochromatic regions of A. thaliana （Melamed-Bessudo and Levy, 2012）, and changes the state of cytosine methylation of a gene flanked by a LINE element located in a region of euchromatin （Saze and Kakutani, 2007）. These studies indicate that the function of DDM1 is not limited to heterochromatin regions and show that it also acts on euchromatic regions in the genome, although the mechanism determining its target specificity remains obscure. Toward understanding the function of DDM1 in the maintenance of global epigenetic state of the genome in higher plants, we performed a genome-wide analysis of cytosine methylation in an antisense-mediated DDMl-knockdown rice line （asDDM1） that exhibits similar characteristics to that of ddml in A. thaliana （Higo et al., 2012; Habu et al., 2015）. Some intrinsic properties of rice genome differ greatly from those of A. thaliana, for example, the content of repeated sequences and their distribution, and therefore rice provides an opportunity to examine the effect of DDM1 deficiency on genomes with a higher content and broader distribution of repeats.
Dear Editor,DECREASE IN DNA METHYLATION1 （DDM1） is a chromatin remodeling protein required for maintenance of cytosine and histone H3K9 methylation in heterochromatin regions in the genome of Arabidopsis thaliana （Gendrel et al., 2002）. A ddm 1 mutant also increases the rate of meiotic recombination in euchromatic but not heterochromatic regions of A. thaliana （Melamed-Bessudo and Levy, 2012）, and changes the state of cytosine methylation of a gene flanked by a LINE element located in a region of euchromatin （Saze and Kakutani, 2007）. These studies indicate that the function of DDM1 is not limited to heterochromatin regions and show that it also acts on euchromatic regions in the genome, although the mechanism determining its target specificity remains obscure. Toward understanding the function of DDM1 in the maintenance of global epigenetic state of the genome in higher plants, we performed a genome-wide analysis of cytosine methylation in an antisense-mediated DDMl-knockdown rice line （asDDM1） that exhibits similar characteristics to that of ddml in A. thaliana （Higo et al., 2012; Habu et al., 2015）. Some intrinsic properties of rice genome differ greatly from those of A. thaliana, for example, the content of repeated sequences and their distribution, and therefore rice provides an opportunity to examine the effect of DDM1 deficiency on genomes with a higher content and broader distribution of repeats.
