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Title: CHEMICAL STRUCTURAL INVESTIGATION OF THE COTTON FIBER BASE AND ASSOCIATED SEED COAT: FOURIER-TRANSFORM INFRARED MAPPING AND HISTOCHEMISTRY

Author
item Himmelsbach, David
item Akin, Danny
item KIM, JUHEA
item HARDIN, IAN

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 11/2/2005
Publication Date: 1/1/2006
Citation: Himmelsbach, D.S., Akin, D.E., Kim, J., Hardin, I.R. 2006. Chemical structural investigation of the cotton fiber base and associated seed coat: fourier-transform infrared mapping and histochemistry. Beltwide Cotton Conferences, National Cotton Council. pp 2398-2409.

Interpretive Summary: Knowledge of the chemical components that surround the cotton fibers that are held in their associated seeds is essential to providing methods to improve the ginning of cotton. To this end both specific chemical dyes and infrared spectral measurements were applied to sections of cotton seed coat with attached fibers. These complementary techniques revealed that: waxes were present at the base of the cotton fiber, pectins surrounded the fiber bases, tannins were found in the outer colored layers and aromatic polymers (lignin) in the colorless layer of tissue. This information suggests that specific chemical or enzymatic treatment of the cotton seed might be effective in assisting the separation of the cotton fiber from the seed and in helping to avoid fiber breakage during ginning.

Technical Abstract: Fourier-transform mid-infrared mapping and histochemical staining are used to reveal the location and relative importance of chemical components involved with the base of cotton fibers and their associated seed coat. These two complementary techniques are focused on the nature of the chemical components that hold cotton fibers at their bases to the seed coat and with other portions of seed coat fragments that are often found as part of the trash component of ginned cotton. Infrared results reveal waxes or long-chain alcohols adjacent to the shank of cotton fiber bases in the outer epidermal tissue in all regions of the cotton seed; uronate anions in the outer epidermis and pigment layers surrounding the bases of the fibers and strongly present in the upper palisade layer tissue of all seed regions; compounds containing carbonyl functionality, acids, and bases, at the juncture of the upper palisade and colorless layers; tannin or pretannin-type aromatic structures in the outer pigment layer and interior to the cells in the epidermal layer of all seed coat regions; and lignin-type aromatics in the “colorless” layer of all regions of the seed coat. The infrared results are complemented by staining with Oil Red O for waxes Ruthenium Red for pectins, acid phloroglucinol for lignins, and vanillin HCl for tannins. The results provide a better understanding of fiber-seed interactions that are important to the development of methods for improving the separation of cotton fibers from seed coats. In turn, this will help to avoid breaking fibers and pulling out seed coat fragments with the fibers during ginning.