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Studies on Roots. IV. Effects of Coumarin and Scopoletin on the Standard Root Growth Pattern of Phleum pratense

Charlotte J. Avers and Richard H. Goodwin
American Journal of Botany
Vol. 43, No. 8 (Oct., 1956), pp. 612-620
Stable URL: http://www.jstor.org/stable/2438877
Page Count: 9
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Studies on Roots. IV. Effects of Coumarin and Scopoletin on the Standard Root Growth Pattern of Phleum pratense
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Abstract

The effects of coumarin and scopoletin on various aspects of root growth have been analyzed from photomicrographic records of epidermal tissue. Coumarin was found to be 3-4 times as effective as scopoletin in inhibiting the peak rate of relative elemental growth, but neither substance greatly inhibited elongation in the apical 400 μ of the epidermis. The most pronounced effect occurred in the rapidly elongating cells, but growing cells approaching maturity also were inhibited markedly. At comparable concentrations scopoletin exerted a greater inhibiting effect on the rate of cell division than coumarin. Coumarin initiated a swelling of the epidermal cells, which became visible as early as 1.5-2 hr. after treatment; whereas scopoletin did not produce this effect. The coumarin-induced swelling is apparently initiated in cells which are about to reach their maximum elemental growth rate at the time the test solution is applied. Although the rapidly elongating cells were especially affected, the reaction extended to portions of the root which had stopped elongating. Scopoletin blocked trichoblast differentiation and strongly inhibited further elongation of the growing root hairs, while trichoblasts continued to develop during coumarin treatments. Thus, while both these unsaturated lactones produce a similar pattern of inhibition of cellular elongation, they differ in their effects on cell division, cell polarity, and trichoblast differentiation. These observations suggest that coumarin and scopoletin affect different portions of the growth machinery.

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