Researchers discovered that as many as a few thousand methylation sites on the plants’ DNA were altered each generation. Although this represents a small proportion of the potentially six million methylation sites estimated to exist on Arabidopsis DNA, it dwarfs the rate of spontaneous change seen at the DNA sequence level by about five orders of magnitude.
This suggests that the epigenetic code of plants — and other organisms, by extension — is far more fluid than their genetic code.
Even more surprising was the extent to which some of these changes turned genes on or off. A number of plant genes that underwent heritable changes in methylation also experienced substantial alterations in their expression — the process by which genes control cellular function through protein production.
This meant that not only was the epigenome of the plants morphing rapidly despite the absence of any strong environmental pressure, but that these changes could have a powerful influence on the plants’ form and function.
Ecker said the results of the study provide some of the first evidence that the epigenetic code can be rewritten quickly and to dramatic effect. “This means that genes are not destiny,” he said. “If we are anything like these plants, our epigenome may also undergo relatively rapid spontaneous change that could have a powerful influence on our biological traits.”