Phaseolus vulgaris: A Diploid Model for Soybean

Along with maize and cassava, common bean is a critical component of diets for many of the developing countries in the world. Beans are an important source of family income and a critical component of the daily diet within African countries where the population is projected to double by 2020. As such, it is the most important edible food legume in the world’s diet. It represents 50% of the grain legumes consumed worldwide, and its production is nearly twice that of chickpeas, the second most consumed food legume. Because poverty limits access to animal protein in developing countries, these peoples turn to common bean as a protein source. From a dietary perspective, it accounts for 40%, 31%, and 15% of the daily intake of total protein in some of the least developed countries, such as Burundi, Rwanda, and Uganda, respectively. And even for a major producer like Brazil, 9% of the dietary protein is provided beans. Common bean is grown in monocultures or as the primary or secondary species in a multicropping system. While the cash value of the crop exceeds $1 billion in the United States, in many ways it is more important elsewhere. For a very poor country such as Myanmar, bean is its most important agricultural export commodity accounting for 10% of their total export income (http://faostat.fao.org/faostat/; verified July 14, 2006). Yield varies significantly, from 638 kg/ha, 671 kg/ha, and 918 kg/ha in Uganda, Rwanda and Burundi, respectively, to 1,944 kg/ha in developed countries. Improving agricultural productivity in Africa and the developing Americas is seen as a means to reverse the trend of increasing poverty and hunger in these regions. Therefore, identifying and minimizing yield limiting factors is an on-going concern for many bean improvement programs. For example, aluminum