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Histophotometric DNA Measurements in Sunflower Seedlings, Crown Gall Tumours, and Habituated Callus Tissues

D. BROEKAERT, C. CAZIER and R. VAN PARIJS
Journal of Experimental Botany
Vol. 27, No. 98 (June 1976), pp. 532-540
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/23688778
Page Count: 9
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Histophotometric DNA Measurements in Sunflower Seedlings, Crown Gall Tumours, and Habituated Callus Tissues
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Abstract

Crown gall tumours of sunflowers were studied with special attention to the relative amount of DNA per nucleus, determined by Feulgen staining and Lison histophotometry. The results show that all tissues of normal germinated sunflower seedlings remain in the diploid state. Crown gall tumours on the hypocotyl consist also predominantly of diploid cells. Two new observations were made. First, it was observed that organ differentiation is occurring (root primordia and young roots) in the tumour tissues. Secondly, it was found that enlarged cambial and parenchymatous cells, scattered or grouped in the tumour, can switch from the mitotic to the endomitotic cell cycle. As a result a polyploid amount of DNA (8-C, 16-C) was measured in the nuclei. Both observations however do not justify the classification of these tumours as typical teratomas. The tendency towards polyploidisation was also demonstrated in habituated sunflower callus cultures by different techniques. The results are discussed in relation to the thesis that nuclear potentialities in vivo are largely reflected in vitro and in the tumour state.

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