The 5S and 45S rDNA sites are useful chromosome landmarks and can provide valuable information about karyotype evolution and species interrelationships. In this study, we employed fluorescence in situ hybridization (FISH) to determine the number and chromosomal location of 5S and 45S rDNA loci in 8 diploid Cucumis species. Two oligonucleotide painting probes specific for the rDNA-bearing chromosomes in C. melo were hybridized to other Cucumis species in order to investigate the homeologies among the rDNA-carrying chromosomes in Cucumis species. The analyzed diploid species showed 3 types of rDNA distribution patterns, which provided clear cytogenetic evidence on the divergence between C. melo and wild diploid African Cucumis species. The present results not only show species interrelationships in the genus Cucumis, but the rDNA FISH patterns can also be used as cytological markers for the discrimination of closely related species. The data will be helpful for breeders to choose the most suitable species from various wild species for improvement of cultivated melon.

Keywords:
Chromosome painting, Cucumis species, Fluorescent in situ hybridization, rDNA
1.
Adams SP, Leitch IJ, Bennett MD, Chase MW, Leitch AR: Ribosomal DNA evolution and phylogeny in Aloe (Asphodelaceae). Am J Bot 87:1578-1583 (2000).
2.
Berjano R, Roa F, Talavera S, Guerra M: Cytotaxonomy of diploid and polyploid Aristolochia (Aristolochiaceae) species based on the distribution of CMA/DAPI bands and 5S and 45S rDNA sites. Plant Syst Evol 280:219-227 (2009).
3.
Cai Q, Zhang D, Lui ZL, Wang XR: Chromosomal localization of 5S and 18S rDNA in five species of subgenus Strobus and their implications for genome evolution of Pinus. Ann Bot 97:715-722 (2006).
4.
Chacón J, Sousa A, Baeza CM, Renner SS: Ribosomal DNA distribution and a genus-wide phylogeny reveal patterns of chromosomal evolution in Alstroemeria (Alstroemeriaceae). Am J Bot 99:1501-1512 (2012).
5.
Chen JF, Staub JE, Tashiro Y, Isshiki S, Miyazaki S: Successful interspecific hybridization between Cucumis sativus L. and C. hystrix Chakr. Euphytica 96:413-419 (1997).
6.
Chen JF, Moriarty G, Jahn M: Some disease resistance tests in Cucumis hystrix and its progenies from interspecific hybridization with cucumber. Progress in cucurbit genetics and breeding research. Proceedings of Cucurbitaceae 2004, the 8th EUCARPIA Meeting on Cucurbit Genetics and Breeding, Olomouc, Czech Republic, 12-17 July, pp 189-196 (2004).
7.
Chung MC, Lee YI, Cheng YY, Chou YJ, Lu CF: Chromosomal polymorphism of ribosomal genes in the genus Oryza. Theor Appl Genet 116:745-753 (2008).
8.
Chung SM, Staub JE, Chen JF: Molecular phylogeny of Cucumis species as revealed by consensus chloroplast SSR marker length and sequence variation. Genome 49:219-229 (2006).
9.
Fukushima K, Imamura K, Nagano K, Hoshi Y: Contrasting patterns of the 5S and 45S rDNA evolutions in the Byblis liniflora complex (Byblidaceae). J Plant Res 124:231-244 (2011).
10.
Garcia-Mas J, Monforte AJ, Arús P: Phylogenetic relationships among Cucumis species based on the ribosomal internal transcribed spacer sequence and microsatellite markers. Plant Syst Evol 248:191-203 (2004).
11.
Garg N, Sidhu AS, Cheema DS: Systematics of the genus Cucumis: a review of literature. Haryana J Hortic Sci 36:192-197 (2007).
12.
Ghebretinsae AG, Thulin M, Barber JC: Relationships of cucumbers and melons unraveled: molecular phylogenetics of Cucumis and related genera (Benincaseae, Cucurbitaceae). Am J Bot 94:1256-1266 (2007).
13.
Han Y, Zhang Z, Liu J, Lu J, Huang S, Jin W: Distribution of the tandem repeat sequences and karyotyping in cucumber (Cucumis sativus L.) by fluorescence in situ hybridization. Cytogenet Genome Res 122:80-88 (2008).
14.
Han Y, Zhang T, Thammapichai P, Weng Y, Jiang J: Chromosome-specific painting in Cucumis species using bulked oligonucleotides. Genetics 200:771-779 (2015).
15.
Huang S, Li R, Zhang Z, Li L, Gu X, et al: The genome of the cucumber, Cucumis sativus L. Nat Genet 41:1275-1281 (2009).
16.
Jeffrey C: A new system of Cucurbitaceae. Bot Zhurn 90:332-335 (2005).
17.
Jiang JM, Gill BS, Wang GL, Ronald PC, Ward DC: Metaphase and interphase fluorescence in situ hybridization mapping of the rice genome with bacterial artificial chromosomes. Proc Natl Acad Sci USA 92:4487-4491 (1995).
18.
Kerje T, Grum M: The origin of melon, Cucumis melo: a review of the literature. Acta Hortic 510:34-37 (2000).
19.
Lan T, Albert VA: Dynamic distribution patterns of ribosomal DNA and chromosomal evolution in Paphiopedilum, lady's slipper orchid. BMC Plant Biol 11:126 (2011).
20.
Li KP, Wu YX, Zhao H, Wang Y, Lü XM, et al: Cytogenetic relationships among Citrullus species in comparison with some genera of the tribe Benincaseae (Cucurbitaceae) as inferred from rDNA distribution patterns. BMC Evol Biol 16:85 (2016).
21.
Liu C, Liu J, Li H, Zhang Z, Han Y, et al: Karyotyping in melon (Cucumis melo L.) by cross-species fosmid fluorescence in situ hybridization. Cytogenet Genome Res 129:241-249 (2010).
22.
Luan F, Delannay I, Staub JE: Chinese melon (Cucumis melo L.) diversity analyses provide strategies for germplasm curation, genetic improvement, and evidentiary support of domestication patterns. Euphytica 164:445-461 (2008).
23.
Maluszynska J, Heslop-Harrison JS: Physical mapping of rDNA loci in Brassica species. Genome 36:774-781 (1993).
24.
Périn C, Hagen S, De Conto V, Katzir N, Danin-Poleg Y, et al: A reference map of Cucumis melo based on two recombinant inbred line populations. Theor Appl Genet 104:1017-1034 (2002).
25.
Ran Y, Hammett KRW, Murray BG: Phylogenetic analysis and karyotype evolution in the genus Clivia (Amaryllidaceae). Ann Bot 87:823-830 (2001).
26.
Renner SS, Schaefer H, Kocyan A: Phylogenetics of Cucumis (Cucurbitaceae): cucumber (C. sativus) belongs in an Asian/Australian clade far from melon (C. melo). BMC Evol Biol 7:58 (2007).
27.
Sebastian P, Schaefer H, Telford IR, Renner SS: Cucumber (Cucumis sativus) and melon (C. melo) have numerous wild relatives in Asia and Australia, and the sister species of melon is from Australia. Proc Natl Acad Sci USA 107:14269-14273 (2010).
28.
Seijo JG, Lavia GI, Fernandez A, Krapovickas A, Ducasse D, Moscone EA: Physical mapping of the 5S and 18S-25S rRNA genes by FISH as evidence that Arachis duranensis and A. ipaensis are the wild diploid progenitors of A. hypogaea (Leguminosae). Am J Bot 91:1294-1303 (2004).
29.
Shan F, Yan G, Plummer JA: Cyto-evolution of Boronia genomes revealed by fluorescent in situ hybridization with rDNA probes. Genome 46:507-513 (2003).
30.
Weiss-Schneeweiss H, Tremetsberger S, Schneeweiss G, Parker JS, Stuessy TF: Karyotype diversification and evolution in diploid and polyploid South American Hypochaeris (Asteraceae) inferred from rDNA localization and genetic fingerprint data. Ann Bot 101:909-918 (2008).
31.
Whitaker TW, Bemis WP: Cucurbits, Cucumis, Citrullus, Cucurbita, Lagenaria (Cucurbitaceae), in Simmonds NW (ed): Evolution of Crop Plants, pp 64-69 (Longman, London 1976).
32.
Whitaker TW, Davis GN: Cucurbits: Botany, Cultivation and Utilization (Interscience, New York 1962).
33.
Yang LM, Koo DH, Li DW, Zhang T, Jiang JM, et al: Next-generation sequencing, FISH mapping, and synteny-based modeling reveal mechanisms of decreasing dysploidy in Cucumis. Plant J 77:16-30 (2014).
34.
Zamir D: Improving plant breeding with exotic genetic libraries. Nat Rev Genet 2:983-989 (2001).
35.
Zhang Y, Cheng C, Li J, Yang S, Wang Y, et al: Chromosomal structures and repetitive sequences divergence in Cucumis species revealed by comparative cytogenetic mapping. BMC Genomics 16:730 (2015).
36.
Zhou XH, Qian CT, Lou QF, Chen JF: Molecular analysis of introgression lines from Cucumis hystrix Chakr. to C. sativus L. Sci Hortic 119:232-235 (2009).
© 2016 S. Karger AG, Basel
2016
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.