The Medicago truncatula reference accession A17 has an aberrant chromosomal configuration.
Medicago truncatula (barrel medic) has emerged as a model legume and accession A17 is the reference genotype selected for the sequencing of the genome. In the present study we compare the A17 chromosomal configuration with that of other accessions by examining pollen viability and genetic maps of intraspecific hybrids. Hybrids derived from crosses between M. truncatula accessions, representative of the large genetic variation within the germplasm collection, were evaluated for pollen viability using Alexander's stain. Genetic maps were generated for the following crosses: SA27063 x SA3054 (n = 94), SA27063 x A17 (n = 92), A17 x Borung (n = 99) and A17 x A20 (n = 69). All F(1) individuals derived from crosses involving A17 showed 50% pollen viability or less. Examination of the recombination frequencies between markers of chromosomes 4 and 8 revealed an apparent genetic linkage between the lower arms of these chromosomes in genetic maps derived from A17. Semisterility and unexpected linkage relationship are both good indicators of a reciprocal translocation. The implications of the A17 distinctive chromosomal rearrangement on studies of genetic mapping, genome sequencing and synteny between species are discussed.
Kamphuis
Lars G
LG
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Williams
Angela H
AH
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
D'Souza
Nola K
NK
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Pfaff
Theo
T
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Ellwood
Simon R
SR
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Groves
Emma J
EJ
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Singh
Karam B
KB
CSIRO Plant Industry, Private Bag 5, Wembley WA 6913, Australia.
Oliver
Richard P
RP
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.
Lichtenzveig
Judith
J
Australian Centre for Necrotrophic Fungal Pathogens (ACNFP), State Agricultural Biotechnology Centre, Department of Health Sciences, Murdoch University, South Street, Murdoch WA 6150, Australia.|CSIRO Plant Industry, Private Bag 5, Wembley WA 6913, Australia.|Centre for Legumes in Mediterranean Agriculture (CLIMA), University of Western Australia, Crawley WA 6009, Australia.
D002874:Chromosome Mapping; D008040:Genetic Linkage; D006824:Hybridization, Genetic; D046913:Medicago truncatula / Q000235:genetics*; D051479:Plant Infertility; D012015:Reference Standards; D014178:Translocation, Genetic