CYTOTAXONOMY OF THE CHARACEAE: KARYOTYPE ANALYSIS OF NITELLA OPACA AND NITELLA FLEXILIS

The haploid chromosome complement of Nitella flexilis ( n = 12) is composed of two quite different basic karyotypes. One of these is symmetrical and appears to be identical to the karyotype of N. opaca ( n = 6), and the other is quite asymmetrical and seems to be identical to that of an apparently u...

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Bibliographic Details
Published in:American Journal of Botany
Main Author: Sawa, Takashi
Other Authors: National Science Foundation
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 1965
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Online Access:http://dx.doi.org/10.1002/j.1537-2197.1965.tb07272.x
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Summary:The haploid chromosome complement of Nitella flexilis ( n = 12) is composed of two quite different basic karyotypes. One of these is symmetrical and appears to be identical to the karyotype of N. opaca ( n = 6), and the other is quite asymmetrical and seems to be identical to that of an apparently undescribed dioecious Nitella from Kansas ( n = 6). This may indicate that the monoecious N. flexilis has arisen through hybridization between two dioecious species. Although heteromorphic sex chromosomes were not observed in either species, it appears that female and male potentialities are confined to separate basic chromosome complements and mechanisms determining the monoecious and dioecious states are in close relation to ploidy.