Improving on nature
Conventional plant breeding involves the controlled inter-crossing of parental lines that each have desirable characteristics, followed by generations of selection within the progeny to identify elite genotypes that have the desired combinations. This is the backbone of crop improvement in all crops and is responsible for most of the gains made in yield, agronomic performance, and disease resistance. However, it is limited to the possibilities achievable using the natural genetic variation within the gene pool of the crop species.
Plant breeding can be used to introduce new product quality traits that may be already present within the gene pool of the species, such as higher oil content or different fatty acid composition. Canola quality rapeseed was developed in this way by combining naturally-occurring genes that reduced the content of two nutritionally undesirable components, erucic acid in the oil and glucosinolates in the protein meal. Varieties of seed oils with increased oleic acid content have also been developed in some species using conventional plant breeding.
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Conventional plant breeding involves controlled pollination followed by generations of selection within progeny for desired combinations of traits.
Where natural variation is insufficient to achieve the desired trait, mutagenic treatments may be used to create additional genetic variation.
New DNA can be introduced to create GM plants with desired genetic traits, using either biolistics (gene-gun) or Agrobacterium transformation.
A targeted gene can be ‘silenced’ by introducing a construct that triggers degradation of the gene’s message, preventing its translation into protein.
Genes can be enhanced or inactivated by using ‘molecular scissors’ to replace or remove short sequences of DNA at highly specific locations.
Plants can be engineered to make new products by incorporating novel gene sets that encode specific enzymes or entire metabolic pathways.