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GROWTH AND ORGANIZED DEVELOPMENT OF CULTURED CELLS IV. THE BEHAVIOR OF THE NUCLEUS
Author(s) -
Mitra J.,
Mapes Marion O.,
Steward F. C.
Publication year - 1960
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1960.tb07137.x
Subject(s) - biology , ploidy , polyploid , multinucleate , nucleus , botany , cell division , protoplasm , totipotent , explant culture , phloem , microbiology and biotechnology , cell , genetics , cellular differentiation , cytoplasm , in vitro , gene
M itra , J., M arion O. M apes , and F. C. S teward . (Cornell U., Ithaca, New York.) Growth and organized development of cultured cells. IV. The behavior of the nucleus. Amer. Jour. Bot. 47(5) : 357—368. Illus. 1960.–The nuclei and the chromosomes of carrot cells have been examined at various stages throughout the following sequence: (1) growth of a tissue culture from a preformed explant of secondary phloem from the carrot root; (2) growth and multiplication of carrot cells freely suspended in a liquid medium; (3) growth and re‐formation of organs (roots) and whole plants (including flowers) from cells in the freely suspended state. The cells of the carrot are normally diploid (2 n = 18), the cells which develop in the explant are also diploid, and the cells of the re‐formed organs, and even the flowers developed upon plants grown from cells, are also normal and diploid; normal meioses also occur. Nevertheless, the wide range in growth and form of the freely suspended cells is accompanied by a rich diversity of cytological conditions; these include tetraploid and highly polyploid nuclei which divide, haploidy and such chromosomal aberrations as di‐ and even tri‐centric bridges. Two division figures showing chromosome numbers at different levels of ploidy were seen within the confines of one large cell, and, in another, 2 adjacent division figures were observed with chromosome numbers lower than diploid. Small thick‐walled, densely protoplasmic cells divide to form bi‐ and tetra‐nucleate conditions, and in a giant cell a highly multinucleate condition has been seen. Despite this, however, all the regenerated roots and plants yet examined are normally diploid. The implications of these events are discussed.