Impact of interspecific hybridization of T. pratense × T. medium and backcrossing on genetic variability of progeny
J. Dluhošová, J. Řepková, H. Jakešová, J. Nedělníkhttps://doi.org/10.17221/115/2016-CJGPBCitation:Dluhošová J., Řepková J., Jakešová H., Nedělník J. (2016): Impact of interspecific hybridization of T. pratense × T. medium and backcrossing on genetic variability of progeny. Czech J. Genet. Plant Breed., 52: 125-131.
Red clover (Trifolium pratense L.) is a high-quality fodder crop which has been hybridized successfully with its wild relative zigzag clover (T. medium L.). The aim of this study was to evaluate the genetic impact of interspecific hybridization and subsequent repeated backcrossing on the variability within hybrid progeny genomes. Nuclear DNA content of 800 and 753 hybrid plants from F7/F8 and F8/F9 generations, respectively, was measured by flow cytometry. Resulting values were converted to estimated chromosome counts, which were successfully validated on a sample of 28 plants by counting mitotic chromosomes. The two generations showed a similar distribution of various chromosome counts ranging from 22 to 47 chromosomes. In total, 24.0% and 34.3% of plants from the two generations had different numbers of chromosomes from their parental plants. Variability within the hybrid population was assessed by fluorescent in situ hybridization using rDNA probes. Individual plants had a pattern of 5S and 45S rDNA loci rather more similar to that of T. pratense than of T. medium. Numbers of chromosomes with clusters of 5S rDNA ranged from 6 to 14 while those of 45S rDNA varied between 4 and 13. Individual arrangements were almost unique, and some plants possessed also novel formations which were not present in any of the parental species, such as a cluster of 5S rDNA surrounded by 45S rDNA clusters or a 45S rDNA cluster surrounded by 5S rDNA clusters. This suggests complex rearrangements connected with post-hybridization stabilization of hybrid genomes.Keywords:
cytology; FISH; hybrids; rDNA; red clover; zigzag cloverReferences:
Abberton M. T. (2007): Interspecific hybridization in the genus Trifolium. Plant Breeding, 126, 337-342 https://doi.org/10.1111/j.1439-0523.2007.01374.xANSARI H (): Molecular Cytogenetic Organization of 5S and 18S-26S rDNA Loci in White Clover (Trifolium repensL.) and Related Species. Annals of Botany, 83, 199-206 https://doi.org/10.1006/anbo.1998.0806Ansari Helal A., Ellison Nicholas W., Williams Warren M. (2008): Molecular and cytogenetic evidence for an allotetraploid origin of Trifolium dubium (Leguminosae). Chromosoma, 117, 159-167 https://doi.org/10.1007/s00412-007-0134-4Bustamante Fernanda O., Rocha Laiane C., Torres Giovana A., Davide Lisete C., Mittelmann Andréa, Techio Vânia H. (2014): Distribution of rDNA in Diploid and Polyploid Lam. and Fragile Sites in 45S rDNA Regions. Crop Science, 54, 617- https://doi.org/10.2135/cropsci2013.05.0325DOLEZEL J. (2005): Plant DNA Flow Cytometry and Estimation of Nuclear Genome Size. Annals of Botany, 95, 99-110 https://doi.org/10.1093/aob/mci005Falistocco Egizia, Marconi Gianpiero, Falcinelli Mario, Scoles G.J. (2013): Comparative cytogenetic study on Trifolium subterraneum (2 n = 16) and Trifolium israeliticum (2 n = 12). Genome, 56, 307-313 https://doi.org/10.1139/gen-2013-0055Isobe Sachiko, Sawai Akira, Yamaguchi Hidekazu, Gau Mitsuru, Uchiyama Kazuhiro (2002): Breeding potential of the backcross progenies of a hybrid between Trifolium medium × T. pratense to T. pratense. Canadian Journal of Plant Science, 82, 395-399 https://doi.org/10.4141/P01-034I tvanek J., Jaro M., Krenek A., Repkova J. (): Genome assembly and annotation for red clover (Trifolium pratense; Fabaceae). American Journal of Botany, 101, 327-337 https://doi.org/10.3732/ajb.1300340Jakešová H., Řepková J., Hampel D., Čechová L., Hofbauer J. (2011): Variation of morphological and agronomic traits in hybrids of Trifolium pratense × T. medium and a comparison with the parental species. Czech Journal of Genetics and Plant Breeding, 47: 28–36.Jakešová H., Hampel D., Řepková J., Nedělník J. (2014): Evaluation of feeding characteristics in variety Pramedi – interspecific hybrid Trifolium pratense × Trifolium medium. Úroda, 12: 183–186. (in Czech)Kataoka R., Hara M., Kato S., Isobe S., Sato S., Tabata S., Ohmido N. (2012): Integration of Linkage and Chromosome Maps of Red Clover ( Trifolium pratense L.). Cytogenetic and Genome Research, 137, 60-69 https://doi.org/10.1159/000339509Khanlou K.M., Karimi M., Maroufi A., Bockstaele E.V. (2011): Improvement of plant regeneration and Agrobacterium-mediated genetic transformation efficiency in red clover (Trifolium pratense L.). Research Journal of Biotechnology, 6: 13–21.Kirov Ilya, Divashuk Mikhail, Van Laere Katrijn, Soloviev Alexander, Khrustaleva Ludmila (2014): An easy "SteamDrop" method for high quality plant chromosome preparation. Molecular Cytogenetics, 7, 21- https://doi.org/10.1186/1755-8166-7-21Kovarik A., Dadejova M., Lim Y. K., Chase M. W., Clarkson J. J., Knapp S., Leitch A. R. (2008): Evolution of rDNA in Nicotiana Allopolyploids: A Potential Link between rDNA Homogenization and Epigenetics. Annals of Botany, 101, 815-823 https://doi.org/10.1093/aob/mcn019Nedbálková B., Řepková J., Bartošová L. (1995): Germplasm TBZP1, TBZP2, TBZP3, TBZP4 of interspecific Trifolium hybrids. Scientific Studies – Research Institute for Fodder Plants, Ltd. Troubsko, 13: 129–131.Ochatt Sergio J. (2008): Flow cytometry in plant breeding. Cytometry Part A, 73A, 581-598 https://doi.org/10.1002/cyto.a.20562Renny-Byfield S., Wendel J. F. (2014): Doubling down on genomes: Polyploidy and crop plants. American Journal of Botany, 101, 1711-1725 https://doi.org/10.3732/ajb.1400119Řepková J., Nedělník J. (2014): Modern methods for genetic improvement of Trifolium pratense. Czech Journal of Genetics and Plant Breeding, 50: 92–99.Řepková J., Nedbálková B., Holub J. (1991): Regeneration of plants from zygotic embryos after interspecific hybridization within the genus Trifolium and electrophoretic evaluation of hybrids. Scientific Studies – Research Institute for Fodder Plants, Ltd. Troubsko, 12: 7–14.Řepková J., Jungmannová B., Jakešová H. (2003): Interspecific hybridisation prospects in the genus Trifolium. Czech Journal of Genetics and Plant Breeding, 39 (Special Issue): 306–308.Repkova Jana, Jungmannova Barbara, Jakesova Hana (2006): Identification of barriers to interspecific crosses in the genus Trifolium. Euphytica, 151, 39-48 https://doi.org/10.1007/s10681-006-9126-3Taylor Norman L. (2008): A Century of Clover Breeding Developments in the United States. Crop Science, 48, 1- https://doi.org/10.2135/cropsci2007.08.0446Taylor N.L., Quesenberry K.H. (1996): Red Clover Science. Dordrecht, Kluwer Academy Publishing, 170–187.Wang Jing, Liu Juan, Kang Ming (2015): Quantitative testing of the methodology for genome size estimation in plants using flow cytometry: a case study of the Primulina genus. Frontiers in Plant Science, 6, - https://doi.org/10.3389/fpls.2015.00354Williams W (): Evidence of Three Subspecies in Trifolium nigrescens Viv.. Annals of Botany, 87, 683-691 https://doi.org/10.1006/anbo.2001.1399