Mitosis and meiosis of five Plantago species were analyzed. Plantago argyrea, P. patagonica and P. wrightiana contain 2n = 20 chromosomes and P. rhodosperma and P. virginica 2n = 24 chromosomes. Similar modes of evolution of the karyotypes of the 2n = 20 species are suggested. All species are presumed to be tetraploid, arising from 2n = 10 and 2n = 12 ancestors. Structural changes in the karyotype of 2n = 12 species could produce one or more large chromosomes resulting in a decrease in chromosomes from 6 to 5. Consequently, chromosome lengths in 2n = 10 and derived 2n = 20 species could be increased by addition of repetitive DNA along the length of each chromosome to maintain chromosome field. Chromosomes of 2n = 24 species are more symmetrical and presumably more primitive than the 2n = 20 species. Chiasma frequencies in meiotic cells of all five species are similar. This suggests that the majority of changes DNA content are in repetitive DNA.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/276649 |
| Date | January 1987 |
| Creators | Sherman, JoAnn Davis, 1955- |
| Contributors | Ramage, Robert T., Briggs, Robert E. |
| Publisher | The University of Arizona. |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Thesis-Reproduction (electronic) |
| Rights | Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. |
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