Salk Institute researchers and colleagues have sequenced the first full plant epigenome–the rules for how genes are used and when they are switched on and off, based on methylation.

The researchers sequenced this “methylome” of the cress Arabidopsis for every letter of its genetic code, and they have begun to use their sequencing process on the human methylome.

Organisms can change the expression of their genetic material without changing the letters of their genetic code. One of the main ways this is done is through the addition of a chemical unit called a methyl group to a gene (the methyl groups act as on/off switches for genes). Methylation is thought to be an important factor in directing stem cells to develop into different tissues, and problems with methylation are implicated in a number of diseases, including cancer and Huntington’s.

See Also Human gene on/off switches to be mapped