Millennia-long epigenetic fluctuations generate intragenic DNA methylation variance in Arabidopsis populations.

Methylation of CG dinucleotides (mCGs), which regulates eukaryotic genome functions, is epigenetically propagated by Dnmt1/MET1 methyltransferases. How mCG is established and transmitted across generations despite imperfect enzyme fidelity is unclear. Whether mCG variation in natural populations is governed by genetic or epigenetic inheritance also remains mysterious.

Concepts, mechanisms and implications of long-term epigenetic inheritance.

Many modes and mechanisms of epigenetic inheritance have been elucidated in eukaryotes. Most of them are relatively short-term, generally not exceeding one or a few organismal generations. However, emerging evidence indicates that one mechanism, cytosine DNA methylation, can mediate epigenetic inheritance over much longer timescales, which are mostly or completely inaccessible in the laboratory.

Extensive de novo activity stabilizes epigenetic inheritance of CG methylation in Arabidopsis transposons.

Cytosine methylation within CG dinucleotides (mCG) can be epigenetically inherited over many generations. Such inheritance is thought to be mediated by a semiconservative mechanism that produces binary present/absent methylation patterns. However, we show here that, in Arabidopsis thaliana h1ddm1 mutants, intermediate heterochromatic mCG is stably inherited across many generations and is quantitatively associated with transposon expression.

mediated demethylation in tomato activates expression of a gene that stimulates vegetative growth.

Expression of the mammalian DNA demethylase enzyme in plants can be used to induce hypomethylation of DNA. In tomato lines that express a transgene, we observed distinct phenotypes including an increase in the length and number of leaves of primary shoots. As these changes resemble phenotypes observed in plants with strong expression of a member of the family, we investigated in lines the expression levels of members of the gene family, which affect shoot architecture and growth of sympodial units in tomato.

An Improved Binary Vector and Escherichia coli Strain for Agrobacterium tumefaciens-Mediated Plant Transformation.

The plasmid vector pGreenII is widely used to produce plant transformants via a process that involves propagation in Escherichia coli However, we show here that pGreenII-based constructs can be unstable in E. coli as a consequence of them hampering cell division and promoting cell death. In addition, we describe a new version of pGreenII that does not cause these effects, thereby removing the selective pressure for mutation, and a new strain of E.