RFLP marker analysis supports tetrasonic inheritance in Lotus corniculatus L. |
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Authors: | R G Fjellstrom PR Beuselinck J J Steiner |
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Institution: | (1) USDA-ARS, National Forage Seed Production Research Center, 3450 SW Campus Way, Corvallis, OR 97331, USA e-mail: r-fjellstrom@tamu.edu, Present address: R.G. Fjellstrom, USDA-ARS, Rice Research Unit 1509 Aggie Dr., Beaumont, TX 77713, USA, US |
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Abstract: | Lotus corniculatus is a tetraploid (2n=4x=24) perennial forage legume and has been reported to have tetrasomic inheritance for several traits, although it has also
been reported to show disomic inheritance. Molecular markers were used to clarify whether tetrasomic inheritance, disomic
inheritance, or a combination of both, was found within an F2 population arising from a cross between two diverse L. corniculatus accessions. The inheritance of ”tetra-allelic” RFLP markers (markers with four segregating bands) indicated that disomic
inheritance could not account for the phenotypic F2 classes observed, and that only tetrasomic inheritance would explain the observed results. Goodness of fit tests for ”tetra-allelic”
and ”tri-allelic” (three segregating bands) RFLP marker data suggested support for chromosomal-type tetrasomic inheritance.
RFLP genotypes interpreted from autoradiographic signal intensity provided additional support for tetrasomic inheritance and
the occurrence of preferential pairing between parental chromosomes. Bivalent pairing was predominant in the two parental
lines and their F1 hybrid in cytological analyses. L. corniculatus has been classified as both an autotetraploid and an allotetraploid species. RFLP evidence of tetrasomic inheritance gives
support for L. corniculatus being classified as an autotetraploid species. Even though bivalent pairing occurs, as seen in other autotetraploid species,
pairing between any of the four homologous chromosomes is possible. Preferential pairing in the F1 hybrid suggests that genome differentiation appears to be minimal between homologs within an accession, while genome differentiation
is greater between homologs from different accessions of this genetically diverse species.
Received: 16 November 1999 / Accepted: 14 July 2000 |
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Keywords: | Tetrasomic inheritance RFLP markers Lotus corniculatus Birdsfoot trefoil Autotetraploid |
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