Transgenic cotton plants with increased seed oleic acid content

Cottonseed typically contains about 15% oleic acid. Here we report the development of transgenic cotton plants with higher seed oleic acid levels. Plants were generated by Agrobacterium-mediated transformation. A binary vector was designed to suppress expression of the endogenous cottonseed Delta -12 desaturase (fad2) by subcloning a mutant allele of a rapeseed fad2 gene downstream from a heterologous, seed-specific promoter (phaseolin). Fatty acid profiles of total seed lipids from 43 independent transgenic lines were analyzed by gas chromatography. Increased seed oleic acid content ranged from 21 to 30% (by weight) of total fatty acid content in 22 of the primary transformants. The increase in oleic acid content was at the expense of linoleic acid, consistent with reduced activity of cottonseed FAD2. Progeny of some lines yielded oleic acid content as high as 47% (three times that of standard cottonseed oil). Molecular analyses of nuclear DNA from transgenics confirmed the integration of the canola transgene into the cotton genome. Collectively, our results extend the metabolic engineering of vegetable oils to cottonseed and should provide the basis for the development of a family of novel cottonseed oils.