RFLP marker analysis supports tetrasonic inheritance in Lotus corniculatusL.

Lotus corniculatus is a tetraploid (2n=4x=24) perennial forage legume and h as been reported to have tetrasomic inheritance for several traits, althoug h it has also been reported to show disomic inheritance. Molecular markers were used to clarify whether tetrasomic inheritance, disomic inheritance, o r a combination of both, was found within an F-2 population arising from a cross between two diverse L. corniculatus accessions. The inheritance of "t etra-allelic" RFLP markers (markers with four segregating bands) indicated that disomic inheritance could not account for the phenotypic F,classes obs erved, and that only tetrasomic inheritance would explain the observed resu lts. Goodness of fit tests for "tetra-allelic" and "tri-allelic" (three seg regating bands) RFLP marker data suggested support for chromosomal-type tet rasomic inheritance. RFLP genotypes interpreted from autoradiographic signa l intensity provided additional support for tetrasomic inheritance and the occurrence of preferential pairing between parental chromosomes. Bivalent p airing was predominant in the two parental lines and their F, hybrid in cyt ological analyses. L. corniculatus has been classified as both an autotetra ploid and an allotetraploid species. RFLP evidence of tetrasomic inheritanc e gives support for L. corniculatus being classified as an autotetraploid s pecies. Even though bivalent pairing occurs, as seen in other autotetraploi d species, pairing between any of the four homologous chromosomes is possib le. preferential pairing in the F, hybrid suggests that genome differentiat ion appears to be minimal between homologs within an accession, while genom e differentiation is greater between homologs from different accessions of this genetically diverse species.