Physiological and biochemical dissection of fiber development in colored cotton

Colored cotton is a very attractive proposition for the textile industry as it reduces the cost for dying. However, inferior fiber quality and non uniform color make it unsuitable for heavy machine spinning. Due to this reason cultivation of colored cotton on commercial scale has been restricted by cotton growers. The current study was planned to unveil the process of fiber development in isogenic lines of brown, green and white cotton by comparing their fiber length, flavonoid, cellulose, carbohydrate and enzyme activities (SuSy, SPS, acid invertase, Cox, NAD+, NADH, NADP+, and NADPH). White cotton fiber exhibited high cellulose contents (915.81 mg g−1) and long fibers (3.07 cm) as compared to colored cotton fibers with low cellulose content (787.63 and 780.66 mg g−1) and shorter fiber length (2.54 and 2.48 cm). Similarly the amount of flavonoids also varied significantly with maximum concentration (8.67 and 7.13 mg g−1) in brown and green cotton fiber at 5 DPA as compared to white cotton fiber (3.12 mg g−1) at 0 DPA. This high concentration of flavonoid not only lowered the total amount of carbohydrates but also lowered the sucrose transformation rate to developing cotton fiber in colored cotton. The activity of different enzymes (AI, SuSy and SPS, Cox, NAD+/NADH and coenzymes NADP+/NADPH involved in the metabolism of carbohydrates was higher in brown cotton fiber than green cotton fiber. However, high activity of these enzymes did not always correlated with higher amount of cellulose thus indicated the involvement of complex mechanisms for cellulose and flavonoid synthesis during the development of cotton fiber.