Mathematical Meiotic Models of Genome Analysis: Comparison With Molecular Approaches
The analysis of the evolutionary distance between genomes is one of the justifications of genome analysis based on molecular analysis and high resolution mapping. It is also the main objective of estimating affinity differences between genomes by mathematical meiotic models, based on the relative frequencies of diakinesis/metaphase I configurations in polyploid hybrids. Polyploid hybrids are preferred over diploid hybrids because they combine several genomes in the same meiotic cellular environment. The first stage of meiotic pairing, although DNA dependent, is indirect and less DNA specific than the second phase. This involves accurate DNA homology search, often leading to crossing-over and chiasmata. The combination of the two stages results in configurations that contain detailed information on evolutionary divergence at both the DNA level and in a more general biological sense. In polyploids these configurations include multivalents of various shapes. In order to interpret this information in terms of evolutionary distance, different mathematical models have been developed. These correspond in some essential respects, but differ in others. Their relative merits are discussed and it is indicated that some frequently adopted simplifications are not acceptable. Certain autopolyploids suggest considerable spurious divergence between identical genomes as a result of the properties of their meiotic pairing and chiasma system. It is advisable, therefore, not to draw conclusions from hybrids alone.
When this and other complicating factors, including variation in pairing and chiasma patterns, are taken into account, diakinesis and metaphase I configurations can give good information on genome differentiation. This includes differences in DNA sequence and gross structural homology as well as other forms of evolutionary divergence.
KeywordsSynaptonemal Complex Chiasma Frequency Preferential Pairing Chiasma Formation Meiotic Pairing
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- Alonso, LC., and Kimber, G., 1981, The analysis of meiosis in hybrids II. Triploid hybrids, Can.J.Genet.Cytol. 23: 221.Google Scholar
- Darlington, C.D., 1965, “Cytology”. J.and A. Churchill Ltd., London.Google Scholar
- Gill, K.S., Gill, B.S., Endo, T.R., and Friebe, B., 1994, Lack of correspondence between chiasmata and crossovers in wheat, IV Kew Chromosome Conf. p. 71.Google Scholar
- Goodspeed, T.H., and Clausen, R.E., 1928, Interspecific hybridization in Nicotiana VIII. The sylvestris-tomentosa-tabacum hybrid triangle and its bearing on the origin of tabacum, Univ. Cal. Publ. Bot. 11: 245.Google Scholar
- Hamey, Y., Abberton, M.T., Wallace, A.J., and Callow, R.S., 1988, Pairing autonomy and chromosome size, in: “III Kew Chromosome Conference,” P.E. Brandham, ed., HMSO London:241.Google Scholar
- Havekes, F., Jong, J.H. de, and Heijting, C., 1993, Synapsis and chiasma formation in tomato, Abstracts XVII Internat. Congr. Genetics Birmingham p. 132.Google Scholar
- Jones, G.H., 1984, The control of chiasma distribution, in: “Controlling events in meiosis,” C.W.Evans, and H.G.Dickinson, eds., 38th Symp. Soc. Exp. Biologists; Comp. Biologists Cambridge p. 293.Google Scholar
- Jones, G.H., and Vincent, J.E., 1994, Meiosis in autopolyploid Crepis capillaris. II Autotetraploids, Gen orne 37: 497.Google Scholar
- Jongedijk, E., Ramanna, M.S., Sawor, Z., and Hermsen, J.G.T., 1991, Formation of first division restitution (FDR) 2n-gametes through pseudo-homotypic division in ds-1 (desynapsis) mutants of diploid potato: routine production of tetraploid progeny from 2xFDR-2xFDR crosses, Theor. Appl. Genet. 82: 645.CrossRefGoogle Scholar
- Kihara, H., 1930, Genomanalyse bei Triticum und Aegilops, Cytologia 1:263. Kimber, G., and Alonso, L.C. 1981, The analysis of meiosis in hybrids. III. Tetraploid hybrids, Can.J.Genet.Cytol. 23: 235.Google Scholar
- Loidl, J., 1986, Synaptonemal complex spreading in Allium. H. Tetraploid Allium vineale, Genome 28: 754.Google Scholar
- Sears, E.R., 1984, Mutations in wheat that raise the level of meiotic chromosome pairing, in: “Genetic manipulation in plant improvement,” J.P. Gustafson, ed., 16th Stadler Genetics Symp. Columbia MO, pp. 295.Google Scholar
- Steinmetz, M., Uematsu, Y., and Lindahl, K.F., 1987, Hotspots of homologous recombination in mammalian genomes, Trends In Genet. (January):7. Sybenga, J., 1965, The quantitative analysis of chromosome pairing and chiasma formation based on the relative frequencies of MI configurations. II. Primary trisomies, Genetica 36: 339.Google Scholar
- Sybenga, J., 1972, “General Cytogenetics,” North Holland/American Elsevier, Amsterdam, London, New York.Google Scholar
- Sybenga, J., 1975, “Meiotic Configurations,” Springer-Verlag, Berlin Heidelberg New York.Google Scholar
- Sybenga, J., 1976, Quantitative variation in chromosome pairing affinities within a species, Secale cereale, in: “Current Chromosome Research”, K. Jones, and P.E. Brandham, eds., Elsevier/North Holland Biomedical Press p. 143.Google Scholar
- Sybenga, J., 1992, “Cytogenetics in Plant Breeding,” Springer-Verlag, Berlin, Heidelberg, New York.Google Scholar
- Sybenga, J., 1995a, Limitations and pitfalls in the use of quantitative polyploid meiotic models for genome analysis, in:“Methods of Genome Analysis in Plants: their Merits and Pitfals,” P.P. Jauhar, ed., CRC Press, Boca Raton. in press.Google Scholar
- Sybenga, J., 1995b, Meiotic pairing in autohexaploid Lathyrus: a mathematical model, Heredity,in press.Google Scholar