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| Designer Plants |
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| Many years ago, Frederick Steward and his co-workers cultured cells from carrot plants and induced some of them to develop into small embryos. Some of these embryos grew into whole plants. Today, researchers routinely regenerate crops, plants and many other plant species from cultured cells. They use various methods to pinpoint a gene in a culture that contains, say, millions of cells. Suppose the researcher includes a toxic product of a pathogen in the culture medium. If only a few cells carry a gene that confers resistance to the toxin, they will be the only ones surviving. |
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| Once whole plants are regenerated from preselected cultured cells, they can be hybridised with other varieties. The idea is to transfer desired genes to a plant lineage to improve traits (such as better yield efficiency and pest resistance) and crop yields. |
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| Given that possibility, botanists comb the world for seeds of the wild ancestors of potatoes, corn, and other valued plants. They send the seeds that carry the genes from a plants lineage to seed banks. These safe storage facilities preserve the genetic diversity of the food supply for most of the human population. That supply is vulnerable to many kinds of pathogenic fungi, viruses, and bacteria. |
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| To give an example, a new fungal strain of Southern Corn Leaf Blight destroyed much of the 1970 corn crop in the United States. This widespread epidemic happened because all of the plants were genetically similar; they all carried the same gene that conferred susceptibility to the disease. Since then, seed companies have become more attentive to providing genetic diversity in corn. And to introduce diversity into existing varieties, plant breeders must tap into the seeds in seed storage. |
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| The search for beneficial genes is a race against time. Farmers throughout the world want high yields, which many of the genetically uniform varieties provide. They discard older, more diverse varieties. By doing so, they also discard the genetic diversity that is so essential for the future of our food supply. |
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