Botany · Ch 9 — Plant Breeding
New Breeding Techniques (NBT)
New Breeding Techniques (NBT)
New Plant Engineering Techniques, or New Breeding Techniques (NBT), are a collection of methods that speed up and sharpen the development of new traits in plant breeding, often by editing the genome directly at specific DNA locations rather than relying on whole-plant crossing. Figure 9.16 contrasts this with the traditional cross-breeding approach, in which a desired gene has only a 50-50 chance of passing to any individual offspring and can take many generations to spread through a population, against the vector-based genetic-engineering route, in which a gene of interest is cut out of a donor's DNA using a restriction enzyme, spliced into a plasmid (a circular bacterial DNA molecule acting as a vector) using DNA ligase to form a recombinant vector, and then delivered by that vector into the chromosomes of the plant cell, so that essentially all offspring inherit the new gene. The specific approaches used in NBT include genome-editing tools such as CRISPR/Cas9, which cut and modify the genome precisely during the cell's own DNA repair process; oligonucleotide-directed mutagenesis (ODM), which introduces changes at just a few base pairs; cisgenesis, which t …
What this figure shows. A comparative diagram contrasting traditional cross-breeding with vector-based genetic engineering and CRISPR/Cas9 gene editing. The traditional-breeding panel shows a desired gene being combined from two parent plants by ordinary crossing, noting the gene has only a 50-50 chance of passing to any offspring and can take multiple generations to spread through a population. The genetic-engineering panel shows a four-step plasmid-vector process: (1) a circular plasmid DNA molecule is removed from a bacterial cell to act as a vector; (2) DNA containing the gene for the desired trait is cut from a chromosome using a restriction enzyme; (3) a second restriction enzyme cleaves the plasmid and DNA ligase pastes the gene into it, forming a recombinant vector; (4) the vector inserts the gene into the chromosomes of plant cells, so the gene is transmitted to nearly all offspring. A separate CRISPR/Cas9 panel shows prec …