Effect of Six Decades of Selective Breeding on Soybean Protein Composition and Quality: A Biochemical and Molecular Analysis
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- 作者：Ahmed A. Mahmoud ; Savithiry S. Natarajan ; John O. Bennett ; Thomas P. Mawhinney ; William J. Wiebold ; and Hari B. Krishnan
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2006
- 出版时间：May 31, 2006
- 年：2006
- 卷：54
- 期：11
- 页码：3916 - 3922
- 全文大小：316K
- 年卷期：v.54,no.11(May 31, 2006)
- ISSN：1520-5118
文摘
To evaluate the extent of the genetic change and its effects on the seed protein composition of soybeancultivars released during the past 60 years, representative ancestral cultivars and those derived fromselective breeding were grown in a side-by-side comparison. Total seed protein content, determinedby combustion analysis of nitrogen, revealed a decline in the protein content after decades of selectionand breeding. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis comparison of proteinprofiles of the soybean cultivars indicated that relative expression of most of the seed storage proteinshad not varied substantially from the ancestral lines to the present commercial cultivars. There wasnoticeably less 
-subunit of -conglycinin, a protein devoid of sulfur amino acids, in the modern cultivarsrepresented by Mustang, Pioneer 93B09, and Asgrow 3602. Comparison of the amino acid profilesof soybean seed, a benchmark of the protein's nutritional quality, revealed that the ancestral progenitor,G. soja, was significantly higher in cysteine, glutamic acid, histidine, and arginine than either theancestral or the modern cultivars. Selective breeding over the past 60 years minimally affected theoverall amino acid composition. The degree of divergence in the DNA sequence of the genes encodingglycinin and -conglycinin in the ancestral and modern cultivars was investigated using Southernhybridization and the polymerase chain reaction. Even though some restriction fragment polymorphisms could be detected, overall, the banding patterns were remarkably similar among the ancestralcultivars and those derived from them, suggesting a high degree of conservation of seed-storageprotein genes. The results of our study suggest that selection and breeding for yield during the past60 years had no major influence on the protein composition, ostensibly because of limited geneticdiversity among the parental lines.Keywords: -Conglycinin; genetic diversity; glycinin; protein composition; protein quality
-subunit of -conglycinin, a protein devoid of sulfur amino acids, in the modern cultivarsrepresented by Mustang, Pioneer 93B09, and Asgrow 3602. Comparison of the amino acid profilesof soybean seed, a benchmark of the protein's nutritional quality, revealed that the ancestral progenitor,G. soja, was significantly higher in cysteine, glutamic acid, histidine, and arginine than either theancestral or the modern cultivars. Selective breeding over the past 60 years minimally affected theoverall amino acid composition. The degree of divergence in the DNA sequence of the genes encodingglycinin and -conglycinin in the ancestral and modern cultivars was investigated using Southernhybridization and the polymerase chain reaction. Even though some restriction fragment polymorphisms could be detected, overall, the banding patterns were remarkably similar among the ancestralcultivars and those derived from them, suggesting a high degree of conservation of seed-storageprotein genes. The results of our study suggest that selection and breeding for yield during the past60 years had no major influence on the protein composition, ostensibly because of limited geneticdiversity among the parental lines.Keywords: -Conglycinin; genetic diversity; glycinin; protein composition; protein quality