Impact of temperature on the expression of Kennedy Pathway genes in developing soybean seeds

Abstract

McNaughton, A. J. M., Shelp, B. J. and Rajcan, I. 2015. Impact of temperature on the expression of Kennedy Pathway genes in developing soybean seeds. Can. J. Plant Sci. 95: 87–101. The main oil storage molecule, triacylglycerol (TAG), can be created by the Kennedy Pathway. The objective of this study was to determine the impact of growing temperature on the expression of the Kennedy Pathway genes, glycerol-3-phosphate acyltransferase (G3PAT), lysophosphatidic acid acyltransferase (LPAAT), and diacylglycerol acyltransferase 1 (DGAT1), in developing seed of four soybean genotypes with altered fatty acid composition using quantitative polymerase chain reaction. The three growing temperatures were: high, 30°C day/25°C night; normal, 25°C day/20°C night; and low, 20°C day/15°C night. The expression of G3PAT steadily declined following 15 d after flowering (DAF), suggesting that it is likely to be more highly expressed earlier in development than was measured in the study. As a result, the expression of G3PAT did not correspond to fatty acid accumulation. LPAAT expression coincided with accumulation of oleic acid (18:1∆9) and linolenic acid (18:3∆9,12,15) in a temperature-dependent manner. The expression of DGAT1 corresponded to accumulation of linoleic acid (18:2∆9,12), which varied among the soybean genotypes, indicating a genotypic effect on the expression of DGAT1. This study suggests that the expression of the acyltransferase enzymes of the Kennedy Pathway influences the fatty acid composition in seed of four altered fatty acid soybean genotypes.