Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/25/2010
Publication Date: N/A
Technical Abstract: Sulfur, an essential plant nutrient is metabolized into the sulfur-containing amino acids cysteine and methionine and into molecules that protect plants against oxidative and environmental stresses. Our knowledge of how sulfur is assimilated and metabolized in soybean (Glycine max (L.) Merr.) remains largely unknown. Although soybeans are an excellent source of protein, they do not contain high levels of the sulfur-containing amino acids. Several attempts have been made to improve the concentration of sulfur-containing amino acids in soybeans. One commonly used approach involves the expression of heterologous seed proteins rich in sulfur-containing amino acids in soybeans. However, the overall increase in the sulfur-containing amino acids obtained by this approach is still not sufficient to meet the amino acid requirements of monogastric animals. As an alternative approach we are conducting experiments aimed at altering the levels of key sulfur assimilatory enzymes. We have generated several transgenic soybean plants expressing a cytosolic O-acetylserine sulfhydrylase gene. These plants accumulate elevated levels of Bowman-Birk protease inhibitor along with increased levels of cysteine in seeds. Our results reveal that the prospects for increasing the sulfur-containing amino acid content of soybean appear promising. A thorough understanding of the fundamental steps and regulation of thiol metabolism in soybean along with the information from the soybean genome will facilitate the improvement of soybean seed protein quality.