Relation between diacylglycerol acyltransferase activity and oil concentration in soybean

• Published in: Journal of the American Oil Chemists' Society 1998-07, Vol.75 (7), p.775-781
• Main Authors: Settlage, S.B, Kwanyuen, P, Wilson, R.F
• Format: Article
• Language: English
• Subjects: ACEITE DE SOJA; ACILTRANSFERASA; ACYLTRANSFERASE; ACYLTRANSFERASES; Agronomy. Soil science and plant productions; Biological and medical sciences; Developing seed; diacylglycerol acyltransferase; Economic plant physiology; enzyme kinetics; Fundamental and applied biological sciences. Psychology; genetic variation; Genetics and breeding of economic plants; Glycine max; HUILE DE SOJA; modeling; Nitrogen metabolism and other ones (excepting carbon metabolism); Nutrition. Photosynthesis. Respiration. Metabolism; oil; oil accumulation; soybean; SOYBEAN OIL; triacylglycerol; Varietal selection. Specialized plant breeding, plant breeding aims; Yield, quality, earliness, varia
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-998-0225-2

Diacylglycerol acyltransferase (EC 2.3.1.20; DGAT) catalyzes synthesis of triacylglycerol from acyl‐CoA and diacylglycerol. Activity of this enzyme and developmental changes in oil accumulation were estimated at various stages of seed growth in soybean germplasm with phenotypic differences in oil content. Oil deposition in seed of these genotypes followed a sigmoid pattern that was modeled to predict incremental rates of oil accumulation during seed development. A strong positive correlation was found between the estimated peak rate of oil deposition (near the mid‐term of seed development) and oil concentration in mature seed. At saturating substrate levels, DGAT activity measured near the peak rate of oil deposition also was correlated positively with oil phenotype. In the latter stages of seed development, a positive correlation between estimates of enzyme activity at or below the apparent Km for diolein and comparable oil accumulation rates was attributed to reduced synthesis of substrates and/or potential change in affinity for substrate as suggested by an increase in apparent Km for diolein in older seed. These data indicated that DGAT activity may be a rate‐limiting step in triacylglycerol synthesis. However, it is difficult to accept the idea of a single rate‐limiting step at the end of a complex metabolic pathway. Because oil is a quantitatively inherited trait, several genes determine genotypic differences in oil content among soybeans. Hence, DGAT activity may be an indicator of coordinated genetic expression of gene‐products in the entire glycerolipid synthetic pathway for a given genotype. In any case, results of this investigation demonstrated that genotypic differences in DGAT activity contributed to expression of genetic variation in oil content among soybean gemplasm.