A Comparative Analysis of in Vitro Cellulose Synthesis from Cell-Free Extracts of Mung Bean (Vigna radiata, Fabaceae) and Cotton (Gossypium hirsutum, Malvaceae)

A comparison of cellulose synthesized in vitro from primary walls of etiolated mung bean (Vigna radiata) seedlings and secondary walls of cotton fibers (Gossypium hirsutum) was made by applying conditions found to be essential for in vitro cellulose I assembly from cotton (Kudlicka et al., 1995, Plant Physiology, vol. 107, pp. 111–123). Mung bean fractions including the plasma membrane (PM), the first solubilized fraction (SE1), and the second solubilized fraction (SE2), incorporated more radioactive UDP-Glc into the total product than the same fractions from secondary walls. A significant difference was found with the mild digitonin solubilized fraction (SE1), which produced eight times more total product than the SE1 fraction of cotton. However, the SE1 fraction from cotton produced a larger quantity of cellulose (32.1%) than from mung bean (6.9%). Treatment of the in vitro product by acetic/nitric acid reagent (AN) for varying periods of time demonstrated that cellulose synthesized in vitro from mung bean was more easily degraded than cellulose from cotton fibers. This would suggest that cellulose I produced in vitro from the cotton SE1 fraction may have a higher crystallinity and DP than cellulose I produced in vitro from mung bean. The fibrils of cellulose produced by the SE, fraction of mung bean were loosely associated and not arranged into a compact bundle as in case of cellulose I synthesized by the cotton SE1 fraction. The electron diffraction patterns (ED) of both products show reflections characteristic for cellulose I. Products from the SE2 fraction of mung bean and cotton reveal similarities with the cellulose II allomorph synthesized, as well as abundant β-1,3-glucan.