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Title: Proteomic and genetic analysis of glycinin subunits of sixteen soybean genotypes

item Natarajan, Savithiry - Savi
item Bae, Hanhong
item Bailey, Bryan
item Cregan, Perry
item Caperna, Thomas
item Garrett, Wesley
item Luthria, Devanand - Dave

Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2007
Publication Date: 5/5/2007
Citation: Natarajan, S.S., Xu, C., Bae, H., Bailey, B.A., Cregan, P.B., Caperna, T.J., Garrett, W.M., Luthria, D.L. 2007. Proteomic and genetic analysis of glycinin subunits of sixteen soybean genotypes. Plant Physiology and Biochemistry. 45(6):436-444.

Interpretive Summary: Soybean is a rich and inexpensive source of proteins called “storage proteins” for humans and animals. Much information is available on the variation in the amount and types of storage protein in different soybean varieties. To better understand the consequences of changing the protein composition of the soybean seed through breeding or genetic engineering, we need to know more about natural variation of seed proteins that occur in soybeans. The objective of this study was to compare the composition of glycinin and the genes that control the production of glycinin in a diverse group of soybeans including the wild soybean from which cultivated soybean originated. We found that wild soybeans have more glycinin when compared to cultivated soybean. We also saw differences in the DNA sequence of glycinin genes among the different soybeans tested. These results are relevant to understanding factors that impact both food quality and composition in soybean and related plants of the legume plant family. In addition, this investigation will be useful for scientists involved in breeding soybeans with better quality storage proteins.

Technical Abstract: We investigated proteomic and genomic profiles of glycinin, a family of major storage proteins in sixteen different soybean genotypes consisting of four groups including wild soybean (Glycine soja), unimproved cultivated soybean landraces from Asia (G. max), ancestors of N. American soybean, and modern soybean cultivars released between 1975 and 1990. We observed considerable variation in all five glycinin subunits, G1, G2 G3, G4 and G5 using proteomics and genetic analysis. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and mass spectrometry (MS) analysis showed that the wild genotypes had a range of 25 -29 glycinin protein spots that included both acidic and basic polypeptides followed by the ancestors with 24-28, modern cultivars with 24-25, and Asian landraces with 17-23 protein spots. Overall, the wild genotypes have a higher number of protein spots when compared to the other three genotypes. Major variation was observed in acidic polypeptides of G3, G4 and G5 compared to G1 and G2, and minor variation was observed in basic polypeptides of all subunits. Our data indicated that there are major variations of glycinin subunits between wild and cultivated genotypes rather than within the same groups. Based on Southern blot DNA analysis, we observed genetic polymorphisms in group I genes (G1, G2, and G3) between and within the four genotype groups, but not in-group II genes (G4 and G5). This is the first study reporting the comparative analysis of glycinin in a disverse set of soybean genotypes using combined proteomic and genetic analysis.