Gene silencing technology, such as RNA interference (RNAi), is commonly used to 
reduce gene expression in plant cells, and exogenous double-stranded RNA (dsRNA) 
can induce gene silencing in higher plants. Previously, we showed that the 
delivery of double-stranded DNA (dsDNA) fragments, such as PCR products of an 
endogenous gene sequence, into fern (Adiantum capillus-veneris) gametophytic 
cells induces a sequence-specific gene silencing that we termed DNAi. In this 
study, we used a neochrome 1 gene (NEO1) that mediates both red light-induced 
chloroplast movement and phototropism as a model of DNAi and confirmed that the 
NEO1 function was suppressed by the repression of the NEO1 gene. Interestingly, 
the gene silencing effect by DNAi was found in the progeny. Cytosine methylation 
was detected in the NEO1-silenced lines. The DNA modifications was present in 
the transcriptional region of NEO1, but no differences between wild type and the 
silenced lines were found in the downstream region of NEO1. Our data suggest 
that the DNAi gene silencing effect that was inherited throughout the next 
generation is regulated by epigenetic modification. Furthermore, the histone 
deacetylase inhibitor, trichostatin A (TSA), recovered the expression and 
function of NEO1 in the silenced lines, suggesting that histone deacetylation is 
essential for the direct suppression of target genes by DNAi.