Naturally occurring high oleic acid cottonseed oil: identification and functional analysis of a mutant allele of Gossypium barbadense fatty acid desaturase-2

Authors: Shockey, Jay; Dowd, Michael; Mack, Brian; Gilbert, Matthew; Scheffler, Brian; Ballard, Linda; Frelichowski, James - Jim; Mason, Catherine

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2016
Publication Date: 3/1/2017
Citation: Shockey, J., Dowd, M., Mack, B., Gilbert, M., Scheffler, B., Ballard, L., Frelichowski, J., Mason, C. 2017. Naturally occurring high oleic acid cottonseed oil: identification and functional analysis of a mutant allele of Gossypium barbadense fatty acid desaturase-2. Planta. 245:611-622.

Interpretive Summary: Cottonseed oil, once a major food product, has lost significant market share relative to other vegetable oils in recent decades, mostly because of unacceptably high levels of unstable fatty acids in the oil that break down at cooking temperatures. Here we describe the analysis of a type of pima cotton that contains much better oil profiles, and the probable genetic cause for the improved oil properties. The responsible gene will be used as a marker to follow the oil trait during future breeding experiments between this pima cotton variety and commercial upland cottons.

Technical Abstract: Vegetable oils are broadly used in the manufacture of many human and animal nutritional products, and in various industrial applications. Along with other well-known edible plant oils from soybean, corn, and canola, cottonseed oil is a valuable commodity. Cottonseed oil is a co-product derived from the processing of cottonseed fiber. In the past, it was used extensively in a variety of food applications. However, cottonseed oil has lost market share in recent years due to less than optimal ratios of the constituent fatty acids found in either traditional or partially hydrogenated oil. Increased awareness of the negative health consequences of dietary trans-fats, along with the public wariness associated with genetically modified organisms, has created high demand for a naturally-occurring oil with high monounsaturate/polyunsaturate ratios. Here we report the discovery of multiple exotic accessions of pima cotton that contain elevated seed oil oleate content. The genome of one such accession was sequenced, and a mutant candidate fatty acid desaturase-2 (FAD2-1D) gene was identified. The mutant protein produced significantly less linoleic acid in infiltrated Arabidopsis leaf assays, compared to a repaired version of the same enzyme. Identification of this gene provides a valuable resource. Development of markers associated with this mutant locus will be very useful in efforts to breed the high-oleate trait into agronomic fiber accessions of upland cotton.