Abstract
Cottonseed oil is rich in unsaturated fatty acids (UFAs) and serves as an edible oil in human nutrition. Reports suggest that acyl-coenzyme A: diacylglycerol acyltransferases (DGAT) and wax ester synthase/DGAT (WSD1) genes encode a key group of enzymes that catalyze the final step for triacylglycerol biosynthesis and enable an important rate-limiting process. However, their roles in oil biosynthesis and the fatty acid profile of cotton seed are poorly understood. Therefore, the aim of this study was to identify and characterize DGAT and WSD1 genes in cotton plants and examine their roles in oil biosynthesis, the fatty acid profile of cotton seeds, and abiotic stress responses. In this study, 36 GhDGAT and GhWSD1 genes were identified in upland cotton (G. hirsutum) and found to be clustered into four groups: GhDGAT1, GhDGAT2, GhDGAT3, and GhWSD1. Gene structure and domain analyses showed that the GhDGAT and GhWSD1 genes in each group are highly conserved. Gene synteny analysis indicated that segmental and tandem duplication events occurred frequently during cotton evolution. Expression analysis revealed that GhDGAT and GhWSD1 genes function widely in cotton development and stress responses; moreover, several environmental stress and hormone response-related cis-elements were detected in the GhDGAT and GhWSD1 promoter regions. The predicted target transcription factors and miRNAs imply an extensive role of GhDGAT and GhWSD1 genes in stress responses. Increases in GhDGAT3 gene expression with increases in cottonseed oil accumulation were observed. Transformation study results showed that there was an increase in C18:1 content and a decrease in C18:2 and C18:3 contents in seeds of Arabidopsis transgenic plants overexpressing GhDGAT3D compared with that of control plants. Overall, these findings contributed to the understanding of the functions of GhDGAT and GhWSD1 genes in upland cotton, providing basic information for further research.
Highlights
Cotton (Gossypium) is the fifth largest oil crop in the world and the most important natural fiber producing plant
The results of the present study showed that GhDGAT and GhWSD1 genes were frequently duplicated during cotton evolution, with only one pair in each of the GhDGAT1 and GhDGAT3 genes, and over level of AtDGAT3, indicating that the alteration of the oil content and fatty acid composition of transgenic Arabidopsis resulted from the overexpression of GhDGAT3D
The results of the present study showed that GhDGAT and GhWSD1 genes were frequently duplicated during cotton evolution, with only one pair in each of the GhDGAT1 and GhDGAT3 genes, and over five pairs of GhDGAT2 homologs genes identified in upland cotton
Summary
Cotton (Gossypium) is the fifth largest oil crop in the world and the most important natural fiber producing plant. The upland cotton (Gossypium hirsutum, AD1) is the most cultivated, accounting for over 90% of cultivated cotton species due to its high fiber production and widespread environmental adaptation. Cottonseed oil is the primary byproduct of cotton processing, accounting for approximately 16% of the seed’s weight [2]. Cottonseed oil is an excellent edible oil for human consumption due to its high content of unsaturated fatty acids (UFA), consisting of 57.64% linoleic acid (C18:2), 22.92% palmitic acid (C16:0), 15.39% oleic acid (C18:1), and 2.22% stearic acid (C18:0) [3]. High unsaturated fatty acid content has been linked to a reduced risk of cardiovascular diseases. The large amount of cottonseed oil serves as a valuable resource for bioenergy [4]
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