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The variation in the bundle fiber strength measurements of cotton (Gossypium hirsutum L.) fibers due to differences in cellulose crystallinity and chain length have not been examined. This study was conducted to determine the length of the cellulose chains (expressed as the weight-average molecular weight, M(sub w) bar) in the crystalline microfibrillar fragments isolated from different cotton fiber and to relate these values to bundle fiber strength. Crystalline microfibrillar fragments were isolated by treating cotton fibers with acetic acid/nitric acid reagent. The crystalline cellulose was dissolved in a lithium chloride solution of N,N-dimethylacetamide. The 13C-nuclear magnetic resonance spectrum of the cellulose solution showed chemical shifts at 103.1, 73.2, 74.2, 75.8, 78.5, and 59.9 ppm for the glucose carbons. The chemical shifts were similar to the chemical shifts in the 13C-nuclear magnetic resonance spectra of other cellulose solutions. The sharpness of the chemical shifts indicated a true solution of crystalline cellulose. Gel permeation chromatography of the crystalline cellulose solution on three linear columns of 1 X 106 angstrom to 500 angstrom of ultrastyragel in a Waters 150C GPC separated the dissolved crystalline cellulose into a population of different sized molecular weight chains. The weight average molecular weight of the population of cellulose chains in the crystalline cellulose from TM-1 cotton fibers was 1.83 X 10 to the fifth power daltons. The average length of the cellulose chains in the crystalline cellulose (measured as the weight average molecular weight of the crystalline cellulose) from different cotton fibers was correlated (r = 0.94) to the bundle fiber strength of the cotton fibers. The data support the conclusion that the average length of cellulose chains in the crystalline cellulose areas of the microfibrils is a component of bundle fiber strength measurements of cotton fibers.

Ligon lintless-1 is a dominant simply inherited mutant of cotton (Gossypium hirsutum L.) containing markedly short cotton fibers with extensively thickened secondary walls. The incorporation of (14C)glucose into crystalline cellulose in the primary and secondary walls was studied to determine the relation between the extent of crystalline cellulose microfibril formation and the pattern of microfibril deposition to the aberrant growth and developmental pattern in the mutant cotton. The results show that the rate of crystalline cellulose formation in the primary walls of the mutant fibers correlates with the reduced rate of fiber elongation and primary wall formation. There is a five-fold increase in the rate of crystalline cellulose formed per millimeter of fiber length during secondary wall formation in the mutant fibers compared to the rate in the wild-type fibers. The Ligon lintless-1 gene mutation affects the growth and development of the cotton fibers with accompanying changes in the rate of formation of crystalline cellulose microfibrils in the primary and secondary walls. This increase in crystalline cellulose microfibrils in secondary walls is most likely due either to an increase in synthetic activity of the individual cellulose synthase complexes or to an increase in number of synthetic complex sites per unit of fiber length in the mutant.