Poster: Cell walls
Abs #
615: Cotton Fiber Growth and Development 3: Effects of exogenous application of GA3 on fiber morphology and secondary wall synthesis
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Presenter: |
Seagull, Robert W, BIORWS@hofstra.edu |
Authors | Seagull, Robert W (A) Gould, Pauline (A) | | Affiliations: |
(A): Hofstra University
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Cotton fiber growth and development requires the plant hormone Gibberellic acid (GA3); however the precise effects of this hormone on fiber have yet to be fully documented. This study investigates the effects of the exogenously applied GA3 on morphological traits of fiber length, diameter, and tapered-tip length, and the secondary wall properties of wall thickness, birefringence, and cellulose content, in the commercial variety G. hirsutum ‘MD51’. Fibers were examined at 10 - 40 days post anthesis for two different application types, first five-days after anthesis or every-other-day until harvest. Untreated fibers exhibit significant increases in all parameters over the study period. The every-other-day application of GA3 (1.0 mg L-1 , 2.7 μM) resulted in fibers that had a significantly greater overall length, had a shorter tapered tip length, a thicker secondary cell wall, increased wall birefringence and a greater cellulose content. Five-day exposure to GA3 (1.0 mg L-1, 2.7 μM) resulted in fibers that were significantly longer than control fibers, but not as long as fibers treated every-other-day. Fibers treated with five-day exposure exhibited thicker secondary cell walls with increased levels of birefringence and increased cellulose content, as compared to control fibers, however these parameters were significantly lower than observed in fibers treated every-other-day. Neither treatment resulted in a significant change in fiber diameter, as compared to controls. The observed changes in fiber morphology and secondary wall synthesis, as a result of hormone application, indicate that GA3 plays an important regulatory role throughout fiber development, influencing both cell expansion properties and secondary wall synthesis.
