SexMeth · Establishment, modulation and inheritance of sexual lineage specific DNA methylation in plants

DNA methylation is an epigenetic mechanism carrying regulatory information across generations in plants and animals. Germlines – called sexual lineages (SLs) in plants – are essential for understanding methylation-based epigenetics because they mediate inheritance and undergo large-scale methylation reprogramming. Germline methylation reprogramming is also crucial for reproduction. However, our understanding of plant SL epigenetics is in its infancy. I have done some of the first and most influential work in plant SL epigenetics, and developed advanced techniques for the isolation and epigenomic analysis of rare plant cell types. Recently my lab discovered that the small RNA-directed DNA methylation pathway, which generally only targets transposons, induces methylation of genes specifically in SLs, thereby regulating gene expression and meiosis. Our results also indicate that genic methylation is established in meiocytes (the origin of the male SL) by soma-derived small RNAs that are attenuated by heat stress, suggesting the hypothesis that environmentally malleable heritable information flows from soma to the germline. We will test our hypothesis and reveal the molecular mechanisms underlying SL-specific DNA methylation in plants by pursuing the following objectives: 1. Determine how SL-specific genic methylation is established in meiocytes2. Reveal how sRNA biogenesis and transport mediate DNA methylation in the male SL3. Elucidate environmental modulation and transgenerational inheritance of SL methylationOur research will reveal how new genomic loci become methylated and stay methylated through cell divisions, and how methylation is adjusted by the environment and carried to the next generation to influence phenotype. This knowledge will revolutionize our understanding of developmentally regulated methylation reprogramming, and will be invaluable for site- and/or cell type- specific engineering of DNA methylation.