Protection of cellulose synthesis in detached cotton fibers by polyethylene glycol

Detachment of the cotton fiber cell from the ovule results in loss of over 90% of the in vivo capacity for synthesis of ¹⁴C]cellulose from ¹⁴C]glucose. However, over 50% of the capacity for cellulose synthesis in the detached fiber population is protected when polyethylene glycol 4000 is present during detachment and incubation. Radioautography shows that approximately full capacity is restored in about half the fibers, whereas the other half of the population are incapable of cellulose synthesis from supplied glucose. The rate of cellulose synthesis in such fibers has a pH optimum of 6 and the optimum polyethylene glycol 4000 concentration is 0.06 molal (−9 bars). Cellulose synthesis in such detached fibers is synergistically stimulated by Ca²⁺ and Mg²⁺ and inhibited by K⁺.