Senior Research Scientist Donald Danforth Plant Science Center St. Louis, Missouri
Body of Abstract: Epigenetically encoded information greatly influences gene expression, yet compared to genetic variation, epigenetic variation is a relatively unexplored and underutilized target for crop improvement. Many plant pathogens manipulate host gene expression to promote disease. Cassava bacterial blight (CBB) is caused by the pathogen Xanthomonas phaseoli pv. manihotis (Xpm). Xpm uses transcription activator-like20 (TAL20) to induce ectopic expression of the cassava gene MeSWEET10a, an event necessary for full virulence. Recently, using tools developed in model systems, we demonstrated that it is possible to edit the epigenome of cassava. We directed DNA methylation to the TAL20 binding site of MeSWEET10a. This methylation blocked TAL20 binding, prevented transcriptional activation of MeSWEET10a by Xpm, and resulted in increased resistance to CBB, a trait that is currently unavailable to breeders. Building off of this success, current work focuses on demonstrating and improving the practicality of this approach toward crop improvement. For example, the initial edits were created using a synthetic zinc finger fused to a component of the RNA-directed DNA methylation pathway. We are now testing additional technologies for editing the epigenome. Data using the readily programmable dCas9 for targeting methylation and efforts toward understanding heritability of epigenetic edits will be discussed. Taken together, this work adds epigenomic editing to the toolbox for plant engineering and crop improvement.