CYTOSKELETAL STABILITY AFFECTS COTTON FIBER INITIATION

The possible involvement of cytoskeletal elements in fiber initiation was examined using cotton (Gossypium hirsutum, variety MD 51) ovules g rown in culture. Ovules cultured in the presence of 1 x 10(-5) M oryza lin (a microtubule-disrupting agent) produced significantly fewer fibe rs. Treatment with 1 x 10(-5) M taxol (a microtubule-stabilizing agent ) induced ovules to produce significantly greater numbers of fibers. C hemical agents modifying the function of microfilaments (i.e., cytocha lasin B or 3 maleimidobenzoyl-N-hydroxy succinimide ester [MBS]) reduc ed fiber production. All the treatments with cytoskeletal-disrupting a gents induced changes in fiber morphology. There is a window of opport unity where cytoskeletal elements function in fiber initiation. Both t he inhibition and stimulation of fiber production occur early in ovule development (between 1 and 3 days postanthesis). After this time, the se chemical agents can induce alterations in fiber morphology but not in the number of fibers produced. These data indicate that cytoskeleta l elements may play separate roles in fiber morphology and initiation mechanisms. Increases in fiber production with the application of taxo l indicate that stabilizing microtubule arrays may stimulate epidermal cells to form fibers. Mimicking the taxol response through manipulati on of microtubule chemistry may provide a mechanism for enhancing in v ivo fiber production.