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Precise manipulation of plant genomes is essential for both fundamental studies and deployment of complex traits, yet it remains limited by two coupled challenges: efficient intracellular delivery of macromolecular cargo and targeted integration of genetic material. In this talk, I will describe two complementary platforms that repurpose naturally evolved molecular machines to enable precision plant genome engineering. First, I will present our work on engineering extracellular contractile injection systems, phage tail-like nanomachines produced by bacteria, for targeted protein delivery to plant cells. By engineering tail fiber specificity, these molecular syringes enabled the first receptor-mediated delivery of functional proteins into plant cells, providing a modular route to cell-type-specific perturbations. I will describe strategies
for cargo loading, receptor targeting, and quantitative characterization of delivery efficiency, as well as emerging design rules governing size constraints and delivery specificity. Second, I will introduce a genome engineering platform based on the avian R2 retroelement that mediates targeted DNA integration into multicopy ribosomal DNA loci. This system enabled efficient installation of large genetic payloads in plants, offering an alternative to double-strand break-dependent approaches that are often inefficient. I will discuss mechanistic insights into integration efficiency, copy number control, and the influence of chromatin context at highly transcribed ribosomal arrays. Together, these platforms illustrate how mining biological diversity for molecular machines and engineering their specificity, modularity, and efficiency can overcome longstanding barriers in programmable plant
engineering.
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