Modification of oil content in cottonseed using chemical mutagenesis

ABSTRACT One of the ways to enhance the economic competitiveness of Upland Cotton (Gossypium hirsutum L.) production in the U.S. is to increase the oil content of cottonseed for domestic use. This study focused on the importance, history and current work at Texas Tech University in modifying cottonseed oil content. Since 1899, cottonseed oil has been a major co-product of fiber production in the U.S. In 2013, cottonseed ranked third behind soybean and corn oils in U.S. annual oilseed production. Cottonseed oil has primarily been used to produce margarine and frying oil. Since most cottonseed oil and meal is marketed domestically, improving the value of cottonseed represents a potential strategy to enhance the gross value of cotton produced in the U.S. Work at Texas Tech University initially concentrated on decreasing the total oil content within cottonseed. Researchers hypothesized that photosynthetic energy, normally used to make lipids in the seed, could be diverted to enhanced cellulose deposition increasing total lint yield. Lines with as low as 11 to 15% oil were identified from our mutant populations (Auld & Bechere, 2003). However, the low oil lines failed to demonstrate an increase in cotton lint yield. It is hypothesized that lines originally selected for high or low oil content will consistently contain high or low oil content from generation to generation showing heritability of the trait. It is also hypothesized that seeds with higher oil content will have a higher weight than those lines with lower oil content. The objective of this research was to identify increased oil content in generations following mutation of the original selections. In addition, this study also attempted to identify a correlation between seed weight and oil content. Oil contents of delinted seeds currently range from 15 to 33% in Upland cotton varieties and higher levels may be developed. Work in ours and in Dr. Kent Chapman’s laboratory at the University of North Texas have identified individual lines with 26 to 30% oil content as determined by Time Domain Nuclear Magnetic Resonance (NMR). It is also hypothesized that seed weight is dependent on oil content. In May of 2013 three mutant cultivars (Acala 1517-99 (M5), FiberMax 958 (M5), and TAM 94L-25 (M2)) were increased at the Texas Tech University Quaker Research Farm. At the end of the growing season individual space plants were harvested from each variety, delinted and evaluated for oil content and seed weight. High and low oil space plants were identified from each cultivar and grown in greenhouse and farm environments in 2014. Once harvested, space plants from each cultivar were once again evaluated for oil content and seed weight. Lines exhibiting consistency of oil content from generation to generation were identified and will continue to be studied for heritability of the trait. Seed oil content and weight were analyzed to identify a correlation using SAS (Corr and Glimimx). With continued improvement and research it is hoped to develop the elite lines within each population required for commercialization.