Transgenerational inheritance of the altered DNA methylation patterns induced by one (Hg<sup>2+</sup>) of the heavy-metal stresses at a mild concentration (50 µm) in the S0 plants (marked as S0-Hg<sup>2+</sup> (50 µm) across two successive selfed generations (S1 and S2).
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Abstract
<p>Examples of hypomethylated patterns in the heavy-metal treated S0-generation plants, which showed “inheritance”, “new pattern” (further hypomethylation), and “reversion” to wild-type in the S1 generation (A and B), but were then stably inherited in the S2 generation (D and E). The <i>Hombox gene</i> (<b>A</b>) detected hypomethylation in S0-Hg<sup>2+</sup> (50 µm) (marked with arrowhead) which in the S1 generation showed all three types of patterns, “inheritance” (plants #12 and #14, marked with arrowheads), “reversion” (plants #11 and #13, marked with arrows), and a new pattern that cannot be explained by segregation alone, and therefore most likely is associated with further methylation modification, i.e., further hypomethylation (marked with asterisks). The <i>DNA-binding protein</i><b>-</b><i>encoding gene</i> (<b>B</b>), plants #11 and #13 showed heritable DNA methylation patterns (marked with arrowhead). <b>C</b>, Hybridization of the <i>osHMA8</i> gene to genomic DNAs of 20 randomly chosen mock S1 plants which are selfed progenies of one wild-type control individual (Mock S0); monomorphic pattern indicate stable inheritance of intrinsic methylation patterns in the ground control plants. <b>D</b> and <b>E</b> are examples of changed methylation pattern in S2 generation (probe, <i>DNA-binding protein</i>). <b>D</b>, S2 generation showed complete inheritance of altered DNA methylation patterns in 20 randomly selected self-pollinated progenies of S1–4 (the upper band was lost in all plants, marked with asterisks); <b>E</b>, S2 generation showed complete inheritance of altered DNA methylation patterns in 20 randomly selected self-pollinated progenies of S1–11. <b>F</b>, Hybridization of the <i>osHMA8</i> to genomic DNAs of 20 randomly chosen Mock S2 plants which are selfed progenies of one Mock S1 individual; monomorphic patterns indicate stable inheritance of the default methylation pattern of wild-type control plants.</p