Can we improve the nutritional quality of legume seeds?

The Food and Agriculture Organization statistics for 2001 (http://apps.fao.org/page/collections? subset agriculture) show that 274 million metric tons of grain legumes were produced across the world, of which 177 million were soybeans (Glycine max; one-half of which were produced in the U.S.) compared with 2 trillion metric tons of cereals. Legume seeds are put to a myriad of uses, both nutritional and industrial, and in some parts of the developing world they are the principle source of protein for humans. They form a very important part of our diet and that of other animals. However, compared with meat, our main source of protein, legumes are deficient in sulfur-containing amino acids. Legume seeds are also an important source of dietary minerals, with the potential to provide all 15 of the essential minerals required by man (Grusak, 2002). The concentrations of certain minerals (especially Fe, Zn, and Ca), however, are low relative to animal food products. Some legumes contain compounds detrimental to our diet, so for this reason and those above, it is desirable to improve their quality. Here, we concentrate on the protein, carbohydrate, and mineral content of legume seeds, although a major component of some legume seeds is their oil. This oil is mainly consumed indirectly through processed foods such as peanut (Arachis hypogaea) butter or margarine, or via cooking oils. A major goal in this area, on health grounds, is the reduction of the “saturated” forms of lipid in soybean oil, mainly by reduction of palmitate, for which there are both conventional breeding and genetic engineering approaches (Kinney, 1998). Modification of storage compounds, however, can have unforeseen consequences if there are pleiotropic effects or if the plant requires the material for vital processes and not just for storage. Such challenges to plant modification are also outlined here. LEGUME PROTEINS ARE OF TWO DISTINCT CLASSES