Changes in the non-structural carbohydrate content of cotton (Gossypium spp.) fibres at different stages of development.

The neutral sugars (glucose, fructose, and sucrose) and the sugar phosphates (glucose 6-phosphate, glucose 1-phosphate and fructose 6-phosphate) soluble in hot aqueous 80% methanol from the fibres of cotton - Gossypium arboreum L., G. barbadense L., and G. hirsutum L. - were determined at various stages of fibre development. In addition, the (1→3)-β-D-glucan content was measured and in the case of G. arboreum the rate of (1→3)-β-D-glucan and cellulose synthesis was determined with [(14)C]sucrose as the precursor. For each of the species a similar chronology was obtained for the changes in content of the various non-structural carbohydrates. At the early stages of secondary wall formation, glucose and fructose exhibited a maximum which was closely followed by a maximum in the (1→3)-β-D-glucan content and in the sugar phosphates. On the other hand, the sucrose content increased regularly until fibre maturity. The rates of synthesis of (1→3)-β-D-glucan and of cellulose were highest following the maximum in the (1→3)-β-D-glucan content, when the latter was being depleted.