Abstract
An Arabidopsis hpm1 mutant, induced by ion-beam irradiation showed a number of aberrant morphological phenotypes including serrated leaves, inhibited growth and early flowering. Similar to ddm1 and met1 mutants, the hpm1 showed a hypomethylation of 180 bp centromeric repeat. In contrast to the ddm1 and met1 mutants, however, hypermethylation of rDNA and transposons was observed in the hpm1 by Southern blot analyses and bisulfite sequencing. F1 plants from a cross between the hpm1 and the wild-type expressed the hypomethylation of the centromeric repeat DNA.The methylation of rDNA in F1 was not affected in comparison with the wild-type. Our results indicated that DNA methylation of repetitive sequences, rDNA and transposons was affected differently in the hpm1 mutant. Contradictive methylation status in the hpm1 suggested the more complex methylation mechanism than expected previously.
