Cotton fibers can undergo cell division

Ovular culture was used to determine the cell cycle aspects of cotton fiber cells. Each ovule (Gossypium hirsutum, cultivar, MD51 ne) grown under the conditions used has ~10 000 fiber cells at 4 d postanthesis. About 25% of these cells divide when ovules are cultured at 34C. Mitosis occurs after fiber cells differentiate, producing multicelled fibers. The basal and tip cells of multicelled fibers have the same characteristics as the polar ends of single-celled fibers. Most cell division occurs in ovules cultured at 2-3 d postanthesis. Multicelled fibers are rare in ovules cultured at 1 d postanthesis and absent if cultured at 7 d postanthesis. No multicelled fibers are detectable on ovules sampled from the plant regardless of age. Fiber cell division occurs in the absence of exogenous hormones. The addition of IAA and GA3 to the medium lowers the frequency of multicelled fibers. IAA alone further reduces their frequency, while GA3 by itself has no effect. The number of fiber cells per cultured ovule ranges between 9462 and 11 087 and is not significantly different from the 9892 seen in the plant at 4 d postanthesis. These findings show that a subpopulation of fiber cells, fully differentiated in appearance, retain cell cycle functions up to 4 d postanthesis.