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In vitro Studies on Abnormal Growth of Prothalli of the Bracken Fern
Taylor A. Steeves, I. M. Sussex and Carl R. Partanen
American Journal of Botany
Vol. 42, No. 3 (Mar., 1955), pp. 232-245
Published by: Botanical Society of America, Inc.
Stable URL: http://www.jstor.org/stable/2438559
Page Count: 14
You can always find the topics here!Topics: Callus, Ferns, Plant growth, Cultural sustainability, Sugars, Thallus, Minerals, Tumors, Salt mining, Salts
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Prothalli of Pteridium aquilinum grown in sterile culture show in general a higher degree of plasticity than comparable prothalli growing on non-sterile soil, and give rise to a number of abnormal developments. In addition to the generalized forms of abnormality, five distinctive developments of a proliferative nature have been isolated and studied in separate culture. Two types of proliferations have been distinguished. Those of the first type, the filamentous, pincushion, and coralloid proliferations, are considered to be no more than abnormal prothallial colonies, because they bear seemingly functional sex organs and in long-continued culture retain the ability to give rise to normal prothalli. The filamentous and pincushion proliferations are filamentous in structure and resemble the juvenile stage of the prothallus. They bear antheridia only. The coralloid proliferation is composed of club like masses of true tissue bearing antheridia and archegonia sparsely and often possessing well developed vascular strands. In addition to normal prothalli, it produces occasional sporelings and sporeling leaves. The proliferations of the second type, the filamentous pseudocallus and the parenchymatous callus, deviate more radically from the cell types of the normal prothallus, and no longer produce sex organs. The filamentous pseudocallus is basically filamentous but individual filaments tend to broaden near their bases by cell divisions in various planes. Regeneration of partially normal prothalli usually occurs abundantly in the early transfers of this proliferation, but diminishes in later transfers. In two cases it was possible to establish completely normal prothallial colonies from these prothalli. The parenchymatous callus is produced frequently by the filamentous pseudocallus and has also arisen directly from the prothallus. It readily gives rise to the filamentous pseudocallus and the two appear to be phases of the same abnormality. The callus is composed of nodular parenchyma with a limited amount of vascular differentiation. The possibility is discussed that the proliferations of the second type may be tumorous and comparable to bacteria-free crown gall and other higher plant tumors.
American Journal of Botany © 1955 Botanical Society of America, Inc.