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ARS Home » Southeast Area » Raleigh, North Carolina » Soybean and Nitrogen Fixation Research » Research » Publications at this Location » Publication #173242
Title: TWO SOLUBLE DELTA-9 STEAROYL-ACP DESATURASE GENES FROM SOYBEAN

Author
item BYFIELD, GRACE - NC STATE UNIV
item XUE, HUIQIN - NC STATE UNIV
item Upchurch, Robert

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2005
Publication Date: 3/15/2006
Citation: Byfield, G.E., Xue, H., Upchurch, R.G. 2006. Two soluble delta-9 stearoyl-acp desaturase genes from soybean. Crop Science. Vol. 46:840-846.

Interpretive Summary: The delta 9 stearoyl acyl-carrier protein desaturase (SACPD) gene of soybean encodes a soluble desaturase enzyme that converts stearic to oleic acid. Understanding the regulation of SACPD gene expression and enzyme activity are thus important steps towards developing soybean lines with increased stearic or oleic acid content. We cloned and sequenced the 3391 base pair SACPD gene from soybean cultivar Dare. Comparison of the amino terminal SACPD sequence with other soybean SACPD sequences in a database revealed unique variability at positions 309, 312, 355, and 373. Sequence-specific primers were designed for Real-time RT-PCR (reverse transcriptase-polymerase chain reaction) for this variable region of SACPDs. Sequencing of a second clone from cultivar Dare confirmed that there were two SACPD genes, designated A and B. Survey of 51 soybean lines and cultivars with the gene-specific primers indicated that all 51 had both genes. Differences between SACPDA and B gene expression in soybean tissues while quantifiable were not dramatic. SACPDA and B expression was similar for four seed developmental stages, although at stage 1, 3, and 4, SACPDA expression was 10 to 15% higher than B. Biochemical analysis of the proteins encoded by these two SACPD genes will show if the unique sequence variability uncovered in this study has any relation to SACPD enzyme activity.

Technical Abstract: The delta 9 stearoyl acyl-carrier protein desaturase (SACPD) of soybean [Glycine max (L.) Merrill] encodes a soluble delta-9 desaturase enzyme that converts stearic to oleic acid. Understanding the regulation of SACPD expression and enzyme activity are thus important steps towards developing soybean lines with altered stearic or oleic acid content. Using primers designed to a G. max SACPD EST sequence, a 3391 bp product was cloned and sequenced from cultivar Dare. Comparison of the third SACPD exon protein sequence with other Glycine exon 3 sequences revealed unique amino acid variability at positions 309, 312, 355, and 373. Sequence-specific primers were designed for Real-time RT-PCR (reverse transcriptase-polymerase chain reaction) for this region of exon 3. Diagnostic and specific products were recovered with these primers using Dare cDNA template and Dare genomic DNA. Sequencing of a second genomic clone from Dare confirmed that there were two SACPD genes, designated A and B. Survey of the genomes of 51 soybean lines and cultivars with PCR and the gene-specific primers indicated that all 51 had both genes. Differences between SACPDA and B transcript abundance in soybean tissues while quantifiable were not dramatic. SACPDA and B transcript accumulation at four seed developmental stages between R5 and R6 was essentially parallel, although at stage 1, 3, and 4, SACPDA transcript accumulation was 10 to 15% higher than B. Biochemical analysis of the proteins encoded by these two SACPD genes may determine if the unique amino acid variability uncovered in this study has any relation to enzyme activity.