Effect of chromosome substitution from alien tetraploid cotton species in Upland cotton on (+) and (-) gossypol enantiomer levels in cottonseed

Authors: Bellaloui, Nacer; Saha, Sukumar; Tonos, Jennifer; Scheffler, Jodi; Jenkins, Johnie; McCarty, Jack; STELLY, DAVID - Texas A&M University

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2020
Publication Date: 4/23/2021
Citation: Bellaloui, N., Saha, S., Tonos, J.L., Scheffler, J.A., Jenkins, J.N., McCarty Jr, J.C., Stelly, D.M. 2021. Effect of chromosome substitution from alien tetraploid cotton species in Upland cotton on (+) and (-) gossypol enantiomer levels in cottonseed. Journal of Cotton Science. 25:7-20.

Interpretive Summary: Cottonseed contains high quality protein meal for feed and oil for human consumption. However, gossypol (anti-nutritional component present in cottonseed and other plant organs) has a potential toxicity and detrimental effects on human health and some animals, including chickens and pigs. Therefore, developing new cotton varieties with lower gossypol content is essential to expand the possible uses of cottonseed. There are two types of gossypol (plus and minus). It is desirable to lower the total amount of gossypol and shift the proportion of plus and minus types of gossypol in the seed to favor the plus gossypol. In order to achieve this objective, a chromosome or segment of a chromosome from wild species or related species was inserted into cultivated upland cotton. The nine modified cotton varieties produced by this method, plus the unaltered parent and a commercial variety used as a control were investigated for level of gossypol in cottonseed. These varieties were planted in Florence, SC, USA, in 2013 and in Mississippi State, MS, USA, in 2014. The results showed that seeds of these varieties accumulated different levels of total gossypol and its fractions (plus and minus gossypol). Some of these lines contained lower levels of total gossypol and a higher fraction of plus gossypol than minus gossypol, desirable characteristics for high quality cottonseed meal for human and livestock consumption. This research advanced our understanding of genetic mechanisms associated with different components of gossypol, which is useful knowledge for cotton breeders working to develop low-gossypol cottonseed and expand the utility of the cotton crop to meet food and feed demands.

Technical Abstract: Cottonseed contains high quality protein meal for feed and oil for human consumption, but gossypol in cottonseed has a potential toxicity and detrimental effects, limiting cottonseed use as food for humans and monogastric animals. Germplasm containing lower gossypol content could potentially improve the potential for these uses. The objective of this research was to investigate the influence of specific chromosomes or chromosome segments on the variability and levels of cottonseed total gossypol, (+) gossypol, and (-) gossypol. Chromosomes 02, 04 and short arm of 08 from Gossypium barbadense, or wild species G. tomentosum, or G. mustelinum were individually substituted into G. hirsutum. These nine chromosome substitution lines (CS lines) were investigated for level of cottonseed gossypol. Two field experiments were conducted in different locations (Florence, SC, USA, 2013; and Mississippi State, MS, USA, 2014). Nine chromosome euploid CS lines, TM-1 (the recurrent parent of the CS line), and AM UA48 (cultivar) were used in this study. The results showed significant variation in gossypol level among CS lines. For example, (+) gossypol across two locations ranged from 0.89 to1.47% (a variation of 65.2%), (-) gossypol ranged from 0.62 to 1.01%, and total gossypol ranged from 1.43 to 2.46%. The (+) gossypol constituted the majority of total gossypol, ranging from 55.5 to 65.3% across the two locations. Although location, genotype (CS lines + TM-1, and AM UA48), and their interactions were all highly significant (P<0.0001), location and genotype were the most important factors for the variation for total gossypol and gossypol fractions. Correlation across the two locations showed significant (P<0.0001) positive relationships between total gossypol, (+) gossypol, and (-) gossypol. This research demonstrated significant differences among the nine CS lines, and some CS lines had significantly lower gossypol level in cottonseed. These results benefit cotton breeders’ efforts to select for lower level of gossypol, which could potentially increase the quality of cottonseed meal for human and monogastric livestock uses.