Ion chromatography separation of cotton surface melezitose and raffinose: entomological vs. plant sugars

Authors: Peralta, Donna; Fortier, Chanel; THIBODEAUX, DEVRON - Fiber Physics; Delhom, Christopher; Rodgers Iii, James

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/22/2016
Publication Date: 5/18/2016
Citation: Peralta, D.V., Fortier, C.A., Thibodeaux, D., Delhom, C.D., Rodgers III, J.E. 2016. Ion chromatography separation of cotton surface melezitose and raffinose: entomological vs. plant sugars. Proceedings of the National Cotton Council Beltwide Cotton Conference, January 5-7, 2016, New Orleans, Louisiana. p. 908-912.

Interpretive Summary: Surface carbohydrates may give information about the developmental stage of cotton, as well as carbohydrate metabolism differences amongst different cotton varieties and the propensity of processing issues caused by stickiness. The extent of a stickiness issue relies on many factors and is likely a complex interaction between intricate physical and chemical properties, such as: the type of sugar contamination, the type of insect responsible for contamination, the occurrence of immature fibers and the presence of waxes, salts and amino acids. Certain levels and ratios of the carbohydrates melezitose and trehalulose deposited on the surface of cotton are indicative of either whitefly or aphid contamination, which may cause problems during cotton processing. Obtaining reliable ion chromatography (IC) values for those surface sugars is paramount in diagnosing a contamination source. Since the plant sugars raffinose and sucrose are isomers of melezitose and trehalulose, respectively, it can be difficult to fully separate them from the entomological sugars via IC, especially when the analysis time is shortened. An improved IC method has been developed which separates melezitose and raffinose from one another; in total nine sugars were separated using the new method. By testing the water extracts of five raw cotton samples via our IC method, we have shown decreases in melezitose amounts present, when compared to the previous method. The difference in melezitose amounts were from separating out the raffinose and another unidentified component from the melezitose peak during IC integration. The method illustrates how full and precise IC separation and integration was important in correctly diagnosing the source of surface cotton fiber sugars.

Technical Abstract: According to previous studies, certain levels of the carbohydrates melezitose and trehalulose deposited on the surface of cotton are indicative of either whitefly or aphid contamination, which may cause problems during cotton processing. Obtaining reliable IC values for those surface sugars is paramount in diagnosing a contamination source. Since the plant sugars raffinose and sucrose are isomers of melezitose and trehalulose, respectively, it can be difficult to fully separate them from the entomological sugars via IC, especially when the analysis time is shortened. An improved IC method has been developed which separates melezitose and raffinose from one another; in total nine sugars were separated using the new method. By testing the water extracts of five raw cotton samples via our IC method, we have shown decreases in melezitose amounts present, when compared to the previous method. The difference in melezitose amounts were from separating out the raffinose and another unidentified component from the melezitose peak during IC integration.