A comprehensive study of the use of a homologous promoter in antisense cotton lines exhibiting a high seed oleic acid phenotype.
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As opposed to first-generation biotechnology products, such as pest-resistant crops and herbicide-resistant crops, second-generation products often utilize plant-derived, homologous or heterologous genes and/or promoters. In this study, we evaluated the ability of a promoter from a gene encoding a major storage protein in cottonseed to drive an antisense sequence of the cotton FAD2 gene to down-regulate the activity of Delta-12 desaturase enzyme in cottonseeds. The oleic acid level in the transgenic cottonseeds approximately doubled from the wild-type level of 15%, with a concomitant decrease in the level of linoleic acid. A more extensive study of one line revealed a higher degree of seed-to-seed variability in the transgenic phenotype. A thorough investigation was conducted to determine the impact of the use of a homologous promoter to drive a transgene on the activity of the endogenous promoter. The results showed that the use of the homologous alpha-globulin B promoter for transgenic purposes did not adversely affect the expression of alpha-globulin B storage protein in cottonseed. The results obtained in this investigation on the use of a homologous promoter and antisense technology will be useful in the design of strategies to alter biosynthetic pathways for nutritional quality improvements and for the production of heterologous proteins of commercial value in seeds.