Fluorescent in situ hybridization, C-banding/DAPI, and CMA3-fluorescence were performed to reveal the cytomolecular constitution of the standard (A) and supernumerary (B) chromosomes of an autotetraploid Tradescantia virginiana L. The analyses show that translocations and/or inversions have occurred during the evolution of the T. virginiana karyotype, generating a significant level of structural heterozygosity. Regarding the structural level, the present paper confirms the occurrence of small subterminal duplications and/or inversions in T. virginiana already suggested by previous authors. Interestingly, many of the distal chromosome segments in T. virginiana possess duplicated subterminal telomere clusters, heterochromatin, 5S and 45S rDNAs orderly intermixed and share this complex cytomolecular architecture with the common type of a B chromosome. Based on the obtained results, it is proposed that in T. virginiana the B chromosome may have arisen via excision from the distal region of an A chromosome. The nascent B could have retained much of the ancestral sequence arrangement, including duplicated telomeric cluster(s), heterochromatin and rDNA, but developed a new centromere/kinetochore to successfully propagate through the cell cycle.

Keywords:
B Chromosomes, Heterochromatin, Quadrivalents, rDNA, Telomeres, Tradescantia
1.
Anderson E, Sax K: A cytological monograph of the American species of Tradescantia. Bot Gaz 97:433–476 (1936).
2.
Bennetzen JL: Transposable element contributions to plant gene and genome evolution. Plant Mol Biol 42:251–269 (2000).
3.
Berdnikov VA, Gorel FL, Kosterin OE, Bogdanov VS: Tertiary trisomics in the garden pea as a model of B chromosome evolution in plants. Heredity 91:577–583 (2003).
4.
Bhaduri PN: Application of new technique to cytogenetical reinvestigation of the genus Tradescantia. J Genet 44:87–127 (1942).
5.
Brown WV: Supernumerary chromosomes in a population of Tradescantia edwardsiana. Southwestern Nat 5:49–60 (1960).
6.
Camacho JPM, Sharbel TF, Beukeboom LW: B chromosome evolution. Phil Trans R Soc Lond B 355:163–178 (2000).
7.
Carchilan M, Mikolajewski S, Houben A: Rye B chromosomes are weakly transcribed and might alter the transcriptional activity of A chromosome sequences. Chromosoma 118:607–616 (2009).
8.
Darlington CD: Chromosome behaviour and structural hybridity in the Tradescantiae. J Genet 21:207–286 (1929).
9.
Darlington CD: Chromosome behaviour and structural hybridity in the Tradescantiae. II. J Genet 35:259–280 (1937).
10.
Dhar MK, Friebe B, Koul AK, Gill BS: Origin of an apparent B chromosome by mutation, chromosome fragmentation and specific DNA sequence amplification. Chromosoma 111:332–340 (2002).
11.
Friebe B, Jiang J, Gill B: Detection of 5S rDNA and other repeated DNA on supernumerary B chromosomes of Triticum species (Poaceae). Pl Syst Evol 196:131–139 (1995).
12.
Giles N: Spontaneous chromosome aberrations in Tradescantia. Genetics 25:69–87 (1940).
13.
Giles N: Spontaneous chromosome aberrations in triploid Tradescantia hybrids. Genetics 26:632–649 (1941).
14.
Golczyk H, Hasterok R, Joachimiak AJ: FISH-aimed karyotyping and characterization of Renner complexes in permanent heterozygote Rhoeo spathacea. Genome 48:145–153 (2005).
15.
Golczyk H, Hasterok R, Szklarczyk M: Ribosomal DNA, tri- and bipartite pericentromeres in the permanent translocation heterozygote Rhoeo spathacea. Cell Mol Biol Lett 15:651–664 (2010).
16.
Gottlob-McHugh SG, Levesque M, Mackenzie K, Olson M, Yarosh O, Johnson DA: Organization of the 5S rDNA genes in the soybean (Glycine max (L.)) Merrill and conservation of the 5S rDNA repeat structure in higher plant. Genome 33:486–494 (1990).
17.
Green DM: Muller’s ratchet and the evolution of supernumerary chromosomes. Genome 33:818–824 (1990).
18.
Hauber DP: Supernumerary chromosomes in Tradescantia I. Meiotic behavior of three homologous isochromosomes. Genetica 75:117–121 (1987).
19.
Hunt DR: Sections and series in Tradescantia. American Commelinaceae: IX. Kew Bull 35:437–442 (1980).
20.
Hunt DR: Campelia, Rhoeo, Zebrina united with Tradescantia. Kew Bull 41:401–405 (1986).
21.
Jamilena M, Ruiz Rejón C, Ruiz Rejón M: A molecular analysis of the origin of the Crepis capillaris B chromosome. J Cell Sci 107:703–708 (1994).
22.
Jones K, Jopling C: Chromosomes and the classification of the Commelinaceae. Bot J Linn Soc 65:129–162 (1972).
23.
Jones RN: B chromosomes in plants. New Phytol 131:411–434 (1995).
24.
Jones RN, Houben A: B chromosomes in plants: escapees from the A chromosome genome? Trend Plant Sci 8:417–423 (2003).
25.
Jones RN, Rees H: B Chromosomes (Academic Press, London, 1982).
26.
Jones RN, González-Sánchez M, González-García M, Vega JM, Puertas MJ: Chromosomes with a life of their own. Cytogenet Genome Res 120:265–280 (2008a).
27.
Jones RN, Viegas W, Houben A: A century of B chromosomes in plants – so what? Ann Bot 101:767–775 (2008b).
28.
Kakeda K, Fukui K: Dynamic changes in the morphology of barley chromosomes during the mitotic metaphase stage. Jap J Genet 69:545–554 (1994).
29.
Kenton A, Davies A, Jones K: Identification of Renner complexes and duplications in permanent hybrids of Gibasis pulchella (Commelinaceae). Chromosoma 95:424–434 (1987).
30.
Koller P: Further studies in Tradescantia virginiana var. humilis and Rhoeo discolor. J Genet 26:81–96 (1932).
31.
Malithano DA: Meiotic behaviour of two supernumerary and structurally changed chromosomes in Tradescantia paludosa. Hereditas 81:1–18 (1975).
32.
Maluszynska J, Schweizer D: Ribosomal RNA genes in B chromosomes of Crepis capillaris detected by non-radioactive in situ hybridization. Heredity 62:59–65 (1989).
33.
Marques A, Roa F, Guerra M: Karyotype differentiation in three species of Tripogandra Raf. (Commelinaceae) with different ploidy levels. Gen Mol Biol 33:731–738 (2010).
34.
Mitchell-Olds T, Clauss M J: Plant evolutionary genomics. Curr Opin Plant Biol 5:74–79 (2002).
35.
Nasuda S, Hudakova S, Schubert I, Houben A, Endo TR: Stable barley chromosomes without centromeric repeats. Proc Natl Acad Sci USA 102:9842–9847 (2005).
36.
Parisod C, Holderegger R, Brochmann C: Evolutionary consequences of autopolyploidy. New Phytol 186:5–17 (2010).
37.
Parokonny AS, Kenton AY, Meredith L, Owens SJ, Bennett MD: Genomic divergence of allopatric sibling species studied by molecular cytogenetics of their F1 hybrids. Plant J 2:695–704 (1992).
38.
Puertas MJ: Nature and evolution of B chromosomes in plants: a non-coding but information-rich part of plant genomes. Cytogenet Genome Res 96:198–205 (2002).
39.
Riley UP: Chromosome aberrations in natural populations of Tradescantia paludosa. Nucleus 1:11–44 (1958).
40.
Santos JL, Alfaro D, Sanchez-Moran E, Armstrong SJ, Franklin FCH, Jones GH: Partial diploidization of meiosis in autotetraploid Arabidopsis thaliana. Genetics 165:1533–1540 (2003).
41.
Sax K: Chromosome behaviour and nuclear development in Tradescantia. Genetics 25:523–533 (1937).
42.
Sax K: An analysis of X-ray induced chromosomal aberrations in Tradescantia. Genetics 25:41–68 (1940).
43.
Sax K, Mather K: An X-ray analysis of progressive chromosome splitting. J Genet 37:483–490 (1939).
44.
Schubert I: Chromosome evolution. Curr Opin Plant Biol 10:109–115 (2007).
45.
Schwarzacher T, Ambros P, Schweizer D: Application of Giemsa banding to orchid karyotype analysis. Plant Syst Evol 134:293–297 (1980).
46.
Schweizer D, Ambros PF: Chromosome banding. Meth Mol Biol 29:97–111 (1994).
47.
Swanson CP: The distribution of inversions in Tradescantia. Genetics 25:438–465 (1940).
48.
Swanson CP: Secondary association of fragment chromosomes in generative nucleus of Tradescantia and its bearing on their origin. Bot Gaz 105:108–112 (1943).
49.
Sybenga J: The quantitative analysis of chromosome pairing and chiasma formation based on the relative frequencies of M I configurations. VII. Autotetraploids. Chromosoma 50:211–222 (1975).
50.
Unfried I, Gruendler P: Nucleotide sequence of the 5.8S and 25S rRNA genes and the internal transcribed spacers from Arabidopsis thaliana. Nucleic Acids Res 18:4011 (1990).
51.
Weiss H, Maluszynska J: Chromosomal rearrangement in autotetraploid plants of Arabidopsis thaliana. Hereditas 133:255–261 (2000).
52.
Whitaker TW: Fragmentation in Tradescantia. Am J Bot 23:517–519 (1936).
© 2011 S. Karger AG, Basel
2011
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.