Genetic diversity is a key component of stable agricultural production in a rapidly changing world. The genetic variation found in field crops, fruits, vegetables, ornamentals, other economically important plants, and their wild and weedy relatives is crucial for crop improvement and the development of new agricultural products. This diversity is found both in nature and in traditional agricultural systems. However, both natural plant communities and traditional agriculture face many threats and are being extensively replaced through urbanization, habitat degradation, and the rise of modern agricultural systems that are based on a relatively narrow genetic base.