The Gehring Lab studies plant epigenetics — the heritable information that influences cellular function but is not encoded in the DNA sequence itself.
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How does epigenetic information — heritable information that influences cellular function but is not encoded in the DNA sequence itself — modulate plant growth and development?
Every cell in an organism inherits the same DNA, and yet many organisms are composed of dozens of cell types. If an organism’s DNA is its lexicon, then each cell type chooses specific words to form a story and passes that vocabulary list to its progeny. These words represent the expression of different genes. Using the small plant Arabidopsis thaliana, Mary Gehring is studying these changes, called epigenetics, that can cause differences in gene expression.
Epigenetics includes many ways gene expression can be heritably altered. One way is through the addition of a molecule called a methyl group to cytosine, one of the four bases of DNA. When a section of DNA is methylated, the cell’s transcription machinery reads the DNA differently and some genes are effectively silenced. Such epigenetic changes can have profound effects on traits critical to plants and their seeds. For example, Gehring has determined that altering the methylation state of a single gene is sufficient to cause changes in seed weight and in the timing of certain aspects of seed development.
Methylation is reversible and can change throughout a cell or organism’s life cycle. Gehring is particularly interested in how the methylation state changes during plant reproduction, from gamete cells through seed maturation. These changes in methylation can signal if a gene copy came from the male or female parent. Such imprinted genes are expressed at different levels, depending from which parent they were inherited. Gehring’s lab is studying how several imprinted genes function during seed development, how they are marked as imprinted, and if specific gene imprinting is conserved within the A. thaliana species and among A. thaliana and closely related species.
Methylation patterns can be passed from one cell generation to the next and from one plant to its offspring. Unlike animals, which designate reproductive cells during embryogenesis, plants form reproductive cells as adults, which could allow the methylation changes accrued during a lifetime to be passed to the plant’s progeny. By studying the epigenetic difference between multiple generations of plants, the Gehring lab will see if epigenetic responses to environmental factors can ultimately lead to evolutionary changes.
Gehring began her scientific career at Williams College, earned her doctorate from University of California Berkeley in 2005, and continued her studies as a postdoctoral researcher with Steven Henikoff at the Fred Hutchinson Cancer Research Center. Gehring came to Whitehead Institute in 2010 and was named the Thomas D. and Virginia W. Cabot Career Development Professor by MIT in 2011. In 2020 she was named the Landon T. Clay Career Development Chair at Whitehead Institute.