The relationship between cellulose content and the contents of sugars and minerals during fiber development in colored cotton cultivars

The contents of cellulose, total carbohydrates, sugars (fructose, glucose, galactose, sucrose, and cellobiose), and minerals (nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium) were determined at various stages of fiber development in the brown cotton cultivar ZX-1, the green cotton cultivar G-7, and the white cotton cultivar LMY28 of Gossypium hirsutum L. Cellulose contents during fiber development changed along S-shaped curves among the tested cotton cultivars. The cellulose content was significantly higher in the white cotton cultivar LMY28 than in the colored cotton cultivars ZX-1 and G-7 after 25 days post anthesis (DPA). Sugar and mineral contents showed significant changes during fiber development. Fructose, glucose, galactose, cellobiose, nitrogen, phosphorus, potassium, sulfur, and magnesium contents were essential for cellulose deposition during fiber development. In this study, glucose was shown to be a direct precursor and key sugar in cellulose biosynthesis in cotton cultivars. There may be a special mechanism in colored cotton cultivars that greater amounts of total carbohydrates, especially glucose, and minerals (nitrogen, phosphorus, potassium, sulfur, and magnesium) were consumed by the biosynthesis and deposition of fiber pigments than in the biosynthesis of cellulose. This finding could explain why the cellulose content was significantly lower in the colored cotton cultivars than in white cotton.