A Cytological Study of Ixeris nakazonei (Asteraceae; Lactuceae) in Okinawa Island, the Ryukyus.
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Accession number;99A0864494
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| Title;A Cytological Study of Ixeris nakazonei (Asteraceae; Lactuceae) in Okinawa Island, the Ryukyus. |
| Author;
DENDA T
(Univ. Ryukyus, Okinawa, Jpn)
YOKOTA M
(Univ. Ryukyus, Okinawa, Jpn)
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Journal Title;Shokubutsu Bunrui, Chiri
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Journal Code:L2614A
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ISSN:0001-6799
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VOL.50;NO.1;PAGE.35-42(1999)
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| Figure&Table&Reference;FIG.4, TBL.1, REF.11 |
| Pub. Country;Japan |
| Language;English |
| Abstract;We have investigated the cytological features of Ixeris nakazonei, a species endemic to the Ryukyus, with a putative hybrid origin between I. repens and I. debilis. The chromosome number of I. nakazonei was determined as 2n=32 (tetraploid), 40 (pentaploidand) and 48 (hexaploid), for the first time. Because the chromosome number 2n=32 is numerically intermediate between that of I. repens (2n=16) and I. debilis (2n=48) or the hexaploid of I. nakazonei, and the tetraploid plants always occur side by side with them, the tetraploid of I. nakazonei likely arose from hybridization between I. repens and I. debilis or I. repens and the hexaploid of I. nakazonei. The pentaploid is a very rare cytotype, and considering its chromosome number, may have originated by hybridization between either the tetraploid and I. debilis or the tetraploid and the hexaploid of I. nakazonei. Because the hexaploid of I. nakazonei and I. debilis have the same chromosome number of 2n=48 and I. nakazonei, I. repens and I. debilis all have similar symmetric karyotypes and relatively small chromosomes, we can not infer the origin of the hexaploid based only on the cytological features. (author abst.) |
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