Genetic engineering in food crops

Traditional plant breeding

Earliest forms of agriculture domesticated wild plants

•noted variation in wild food plants

•gathered seeds from the “best”

•plants raised from last year’s “best” still show variation, but over a “better” range

•the “best” could be larger yields, or resistance to frost, disease or drought

•resulted in varieties of food and other crops grown worldwide, both plants and animals

Wild rose on left is ancestor to rose cultivar on right

•Six different vegetables; same wild ancestor; a few thousand years

Cross breeding

•deliberate interbreeding (crossing) of closely related species or varieties to produce new crops with desirable properties

•example, a mildew resistant pea may be crossed with a high-yielding but susceptible pea

•first generation offspring are high-yielding and mildew resistant = hybrid variety

•second generation lack some or all traits (planting seeds of a hybrid crop will not yield a similar crop)

•often takes 15 or more years to breed a new variety

•pests and diseases eventually evolve ability attack new hybrids

Genetic Engineering

•splices a gene from one species and transplants it into the DNA of another species

•creates improved strains of crops and livestock animals

–takes half as much time as traditional breeding to develop a new crop

–cuts costs

–allows for all kinds of potential product development

Genetic Engineering examples

•Gene from firefly transplanted into tobacco; glows when needs watering

•Gene from bacteria transplanted into corn and other crops; plants produce toxin (Bt) that kills pests