(Invited) Carbon Nanodots for Improved Plant Genetic Engineering

Anthropogenic climate change has made the need for more nutritious and stress-tolerant plants indisputable for providing food security. Climate change has decreased the global agricultural productivity by 21% since 1961, and will continue to drop crop yields by 7.4% for every degree-Celsius increase in temperature. CRISPR genetic engineering can enable previously inaccessible crop tolerances to meet the demand for nutritionally-balanced and high-yielding crops. However, plant biomolecule delivery and transformation are two important bottlenecks that prevent plant genetic engineering from reaching its full potential. Nanomaterials have already shown promise to deliver genetic cargoes into plant somatic cells for transient expression of proteins 1 . For most applications in agriculture, however, biomolecules need to be delivered to cells that can give rise to next generation of edited plants, such as germ or stem cells. These cell types are extremely challenging to penetrate and deliver cargoes using traditional approaches, hence forcing researchers to use undifferentiated tissues to transform and go through an arduous regeneration process in tissue culture. This time consuming, inefficient, and highly species dependent approach has been a critical obstacle in plant biology and bioengineering. We have synthesized small (~3 nm) and positively charged (+35 mV) carbon nanodots (CNDs) from glycerol and polyethyleneimine (PEI) using the microwave method. These CNDs showed high entry efficiency into plant stem cells and ability to deliver DNA cargoes into a model plant Nicotiana benthamiana without affecting stem cell viability and differentiation capability. This is a first-time demonstration of nanoparticle uptake by plant stem cells and cargo expression in these cell types. Once we perform CRISPR gene editing in these stem cells, the edited germ cells and seeds will develop automatically from the stem cells, facilitating the creation of edited and improved new plant varieties. References: Demirer, Gozde S., et al. "High aspect ratio nanomaterials enable delivery of functional genetic material without DNA integration in mature plants." Nature nanotechnology 14.5 (2019): 456-464.