Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 14, 2000
Publication Date: N/A
Interpretive Summary: Lotus corniculatus, commonly known as birdsfoot trefoil, is a forage legume grown throughout temperate regions of the world. It has not been clear how traits are inherited in birdsfoot trefoil. Understanding how traits are inherited will aid breeding efforts to make variety improvements in this crop. Birdsfoot trefoil is a tetraploid crop species with fours sets of chromosomes giving rise to disomic inheritance (found in most organisms, which are diploid with two sets of chromosomes)or, alternatively, if it has four copies of the same chromosome set giving rise to tetrasomic inheritance. Molecular marker analyses provided powerful evidence that only tetrasomic inheritance could give rise to the progeny obtained from genetic crosses, making birdsfoot trefoil one of the few tetrasomic crop species. The results also suggest at least two origins of this crop species arising from chromosome doubling of a diploid form or hybrids between two highly related diploid progenitor species that have given rise to the tetraploid forms found today.
Lotus corniculatus is a tetraploid (2n equals 4x equals 24) forage legume reported to have tetrasomic inheritance for several traits. However, tetrasomic segregation has not adequately explained the inheritance of certain traits, and disomic inheritance has also been reported. Restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers were used to clarify whether tetrasomic or disomic inheritance was found within an F2 progeny population from a cross between two diverse accessions. The inheritance of tetra-allelic RFLP markers (markers with four segregating bands) indicates that disomic inheritance cannot account for the phenotypic F2 classes observed, and only tetrasomic inheritance can explain the observed results. Interpreted RFLP genotypes of progeny classes provide additional support for tetrasomic inheritance, along with the first reported occurrence of double reduction in L. corniculatus. Dominant RAPD markers gave slightly better goodness-of-fit t disomic rather than tetrasomic inheritance, although the progeny population was not large enough to adequately reject or accept any single mode of inheritance. 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, pairing between any of four homologous chromosomes is possible.