Assessment of indigenous Nepalese soybean as a potential germplasm resource for improvement of protein in North American cultivars.
Soybeans contain approximately 40% protein and 20% oil and represents an important source of protein in animal rations and human diets. Attempts are being made to increase further the overall protein content of soybeans by utilization of exotic germplasms. In this study, soybean cultivars from Nepal have been characterized and their potential as a germplasm resource for improvement of the protein content and quality of North American cultivars assessed. Soybean cultivars 'Sathia', 'Seti', 'Kavre', and 'Soida Chiny', indigenous to various regions of Nepal, contained 42-45% protein, which is significantly higher in comparison to that of the North American cultivar 'Williams 82' (39%). Fractionation of seed protein by high-resolution two-dimensional gel electrophoresis revealed differences in the protein profiles of these cultivars. Various isoelectric forms of glycinin and beta-conglycinin were identified by comparing the matrix-assisted laser desorption ionization time-of-flight mass fingerprinting data against the National Center for Biotechnology Information nonredundant database. Nepalese cultivar Sathia was distinct, lacking some isoelectric forms of acidic and basic glycinin subunits while expressing other unique forms. The contribution of these unique protein spots present in either Sathia or Williams 82 to the total protein content was quantified using scanning laser densitometry. Distinct restriction fragment length polymorphisms (RFLP) for group 1 glycinin genes were observed among the tested Nepalese genotypes, indicating sequence variation among the cultivars. Conversely, evaluation of RFLP for the genes encoding group 2 glycinins, beta-conglycinin, and Bowman-Birk proteinase inhibitors indicated a high degree of conservation in these genes. Determination of amino acid composition, a reflection of protein quality, indicated that the arginine content of the Nepalese soybeans ranged from 7.7 to 8.1%, which was 5-10% higher than the 7.4% expressed in Williams 82. Additionally, Karve and Seti contained significantly more cysteine than Williams 82. Nepalese high-protein soybeans having a desirable amino acid composition hold potential to increase the protein quality and diversity of North American cultivars.
Krishnan
Hari B
HB
Plant Genetics Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Columbia, Missouri 65211, USA. krishnanh@missouri.edu
Natarajan
Savithiry S
SS
Mahmoud
Ahmed A
AA
Bennett
John O
JO
Krishnan
Ammulu Hari
AH
Prasad
Braj Nandan
BN
D000596:Amino Acids / Q000032:analysis; D052179:Antigens, Plant; D015180:Electrophoresis, Gel, Two-Dimensional; D005838:Genotype; D005916:Globulins / Q000032:analysis / Q000235:genetics; D009390:Nepal; D009656:North America; D012150:Polymorphism, Restriction Fragment Length; D011480:Protease Inhibitors; D055314:Seed Storage Proteins; D012639:Seeds / Q000737:chemistry*; D030262:Soybean Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D013025:Glycine max / Q000737:chemistry* / Q000235:genetics*; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000596:Amino Acids; D052179:Antigens, Plant; D005916:Globulins; D011480:Protease Inhibitors; D055314:Seed Storage Proteins; D030262:Soybean Proteins; C013894:beta-conglycinin protein, Glycine max; C011474:glycinin