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Arachis hypogaea. Normal Megasporogenesis and Syngamy with Occasional Single Fertilization

Ben W. Smith
American Journal of Botany
Vol. 43, No. 2 (Feb., 1956), pp. 81-89
Stable URL: http://www.jstor.org/stable/2438815
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.
Arachis hypogaea. Normal Megasporogenesis and Syngamy with Occasional Single Fertilization
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Abstract

The twenty chromosome pairs of the cultivated peanut, Arachis hypogaea, are differentiated into proximal heterochromatic and distal euchromatic segments, and exhibit regular meiotic behavior in megasporogenesis. Differentiation of the functional, chalazal megaspore actually begins in the cytoplasmic differentiation of the megasporocyte at diakinesis. Gametogenesis is simultaneous in the anthers and ovules of a given flower. The monosporic, seven-celled, eight-nucleate megagametophyte is of the Polygonum ("normal") type, but only the egg and the central cell with its two polar nuclei persist until anthesis. Syngamy occurs 10-18 hr. after anthesis following natural self-pollination, and fails in less than seven per cent of the ovules. Although double fertilization is the rule, 28 cases of single fertilization have been observed in Arachis. Twenty-two ovules contained developing embryos, but triple fusion and endosperm development had failed. Unfertilized eggs were found in six ovules containing 8- or 16-nucleate endosperms.

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