@article{byfield_upchurch_2007, title={Effect of temperature on delta-9 stearoyl-ACP and microsomal omega-6 desaturase gene expression and fatty acid content in developing soybean seeds}, volume={47}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2006.04.0213}, abstractNote={Delta‐9 stearoyl‐ACP (SAD) and microsomal omega‐6 oleate (FAD2) desaturases contribute to the maintenance of lipid fluidity in membranes and the fatty acid composition of storage lipids in seed. Since these enzymes must operate at varying environmental temperatures, they are under constitutive control, but they may also be subject to fine regulation both transcriptionally and posttranscriptionally. We measured transcript accumulation of the seed‐expressed SAD‐A and SAD‐B and FAD2‐1A and FAD2‐1B genes in the seeds of three soybean varieties grown at cool (22/18°C), normal (26/22°C), or warm (30/26°C) temperatures during pod fill. At the cool temperature, transcript accumulation of both the SAD and FAD2‐1 genes was significantly elevated, with FAD2‐1B 2‐ to 10‐fold or greater than FAD2‐1A at 35 d after flowering. Expression of both SAD and FAD2‐1 were significantly decreased in seed that developed at the warm temperature. Decreased FAD2‐1 transcript accumulation at the warm temperature was positively associated with significantly increased oleic and decreased linoleic acid content in the three varieties examined. Decreased SAD transcript accumulation at the warm temperature was positively associated with a significantly increased level of stearic acid but only in the high‐stearate mutant line, A6. We conclude that environmental temperature modulates oleic and linoleic acid in developing seed through regulated FAD2‐1 gene expression, but temperature modulation of stearic acid content in wild‐type soybean may be more complex, involving in addition to SAD‐A and ‐B, plastid thioesterase genes FATA and FATB.
}, number={4}, journal={CROP SCIENCE}, author={Byfield, Grace E. and Upchurch, Robert G.}, year={2007}, pages={1698–1704} }
 @article{byfield_upchurch_2007, title={Effect of temperature on microsomal omega-3 linoleate desaturase gene expression and linolenic acid content in developing soybean seeds}, volume={47}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2007.05.0263}, abstractNote={The mechanism of temperature adaptation in plants, including the formation of polyunsaturates in seed storage lipids, most likely involves transcriptional as well as post‐translational regulation of fatty acid desaturase activity. The present investigation was conducted to measure changes in the transcript accumulation among the three members of the soybean [Glycine max (L.) Merr.] microsomal omega‐3 fatty acid desaturase gene family in response to altered growth temperature during seed development. Microsomal omega‐3 fatty acid desaturases catalyze the insertion of a third double bond into linoleic (18:2Δ9, 12) acid to produce linolenic (18:3Δ9, 12, 15) acid. At 35 d after flowering, transcript accumulation (normalized for soybean actin) of GmFAD3A decreased by 5‐ to 15‐fold, GmFAD3B by 2‐ to 9‐fold, and GmFAD3C by 2‐ to 3‐fold in seeds that developed in a warm (day/night [D/N] = 30/26°C) versus a normal (D/N = 26/22°C) or a cool (D/N = 22/18°C) environment. At this stage of seed development, decreased omega‐3 desaturase gene expression levels were positively associated with reductions of 39 to 50% in the linolenic acid content of seeds of three soybean varieties examined. Thus, transcriptional regulation of the microsomal omega‐3 fatty acid desaturase gene family likely accounts, at least in part, for the reduced linolenic acid levels in soybean seeds grown at elevated temperature.}, number={6}, journal={CROP SCIENCE}, author={Byfield, Grace E. and Upchurch, Robert G.}, year={2007}, pages={2445–2452} }
 @article{byfield_xue_upchurch_2006, title={Two genes from soybean encoding soluble Delta 9 stearoyl-ACP desaturases}, volume={46}, ISSN={["1435-0653"]}, DOI={10.2135/cropsci2005.06-0172}, abstractNote={The Δ9 stearoyl acyl‐carrier protein desaturase (SACPD) gene of soybean [Glycine max (L.) Merrill] encodes a soluble enzyme that converts stearic to oleic acid. Understanding the regulation of SACPD expression and enzyme activity are thus important steps toward developing soybean lines with altered stearic or oleic acid content. Using primers designed to a G. max SACPD cDNA sequence, a 3648‐bp product was cloned and sequenced from the genome of cultivar Dare. Comparison of the third SACPD exon protein sequence with other available Glycine SACPD sequences revealed unique amino acid variability at positions 310 and 313. 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, in this cultivar. Survey of the genomes of 51 soybean lines and cultivars with PCR and the gene‐specific primers indicated that all 51 had both A and B Differences between SACPD‐A and ‐B transcript abundance in soybean tissues, while quantifiable, were not dramatic. SACPD‐A and ‐B transcript accumulation for three seed developmental stages between R5 and R6 was essentially equal. Biochemical analysis of the proteins encoded by these two SACPD genes may reveal whether the amino acid variability uncovered in this study has any relation to enzyme activity.}, number={2}, journal={CROP SCIENCE}, author={Byfield, GE and Xue, H and Upchurch, RG}, year={2006}, pages={840–846} }