CRISPR Plant Engineering
CRISPR editing in plants faces challenges not present in cell culture: delivering editing components across a cell wall, achieving stable germline transmission, regenerating whole plants from transformed cells, and doing this in species with complex polyploid genomes. The workflow is well-established for most crop species but takes weeks to months.
Delivery Methods
Agrobacterium tumefaciens (T-DNA transfer) is the standard method for dicots — peppers, tomatoes, tobacco. The bacterium naturally integrates DNA into plant chromosomes and can be loaded with any construct. Particle bombardment (biolistics) fires DNA-coated gold particles into plant tissue at high velocity — preferred for recalcitrant monocots like maize and wheat. Lipid nanoparticles encapsulate guide RNA / protein complexes for DNA-free editing where regulatory advantages apply.
Regeneration
Transformed cells must be grown on selective media, then induced to regenerate into whole plants through tissue culture — a process that takes 4–16 weeks depending on species. This regeneration bottleneck, more than any molecular step, limits the throughput of plant editing. Pepper regeneration is notably slow compared to tobacco (4–6 weeks) or Arabidopsis (3–4 weeks).
What Can Be Edited
Modern plant CRISPR extends well beyond simple knockouts. Base editors make single C→T or A→G substitutions without cuts, enabling amino acid changes with high precision. Prime editors write new sequences up to ~44 bp into any locus. CRISPRa/i systems activate or suppress transcription without altering the DNA sequence.