Nanoparticle-Mediated Genetic Engineering of Plants

Abstract

Genetic engineering of plants is at the core of sustainability efforts, natural product synthesis, and agricultural crop improvement. The past several decades have brought remarkable progress in biotechnology with the improvement of genome editing and sequencing tools, which stand to advance plant synthetic biology and bioengineering. In agriculture, genetic engineering can be employed to create crops that have increased yields and nutritional value, are resistant to herbicides, insects, diseases, and abiotic stresses, including drought and heat. In pharmaceuticals and therapeutics, genetically engineered plants can be used to synthesize valuable small-molecule drugs and recombinant proteins. Plastids, such as chloroplasts, lack gene silencing pathways and have been demonstrated to have high and stable expression of transgenes. Because chloroplasts are maternally inherited in most plant species, they provide genetic containment in transformed crops. Despite several decades of advancements in biotechnology, many plant species and their plastids remain difficult to genetically transform. Currently, few delivery tools exist that can transfer biomolecules into plant cells and their subcellular compartments, each with limitations. Agrobacterium-mediated delivery is the most commonly used tool for gene delivery into plants. However, Agrobacterium can only perform gene delivery for a narrow range of plant species, cannot be used for DNA-free editing or for transformation of the chloroplast or mitochondrial genomes, and yields random DNA integration into the plant genome. The other commonly used tool for plant transformation is biolistic particle delivery (also known as gene gun) in which gold microparticles are delivered to plant tissues with a high-pressure gene gun. Biolistics can deliver biomolecules into a wider range of plant species and into plastid genomes but faces limitations of low-level and sporadic expression, random DNA integration, plant tissue damage under high bombardment pressures and exposure to vacuum, and requires use of a substantial amount of DNA. Furthermore, gene gun bombardment is a technique that requires specialized facilities and costly materials that limit its widespread use. The lack of versatile, high-throughput tools for biomolecule delivery into plant cells through the rigid and multi-layered cell wall and double lipid bilayer envelopes of organelles represents a significant bottleneck to plant genetic engineering that may be facilitated by nanoparticle technology.

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