Chromosomal evolution and patterns of introgression in helianthus.
Knowledge of the nature and extent of karyotypic differences between species provides insight into the evolutionary history of the genomes in question and, in the case of closely related species, the potential for genetic exchange between taxa. We constructed high-density genetic maps of the silverleaf sunflower (Helianthus argophyllus) and Algodones Dune sunflower (H. niveus ssp. tephrodes) genomes and compared them to a consensus map of cultivated sunflower (H. annuus) to identify chromosomal rearrangements between species. The genetic maps of H. argophyllus and H. niveus ssp. tephrodes included 17 linkage groups each and spanned 1337 and 1478 cM, respectively. Comparative analyses revealed greater divergence between H. annuus and H. niveus ssp. tephrodes (13 inverted segments, 18 translocated segments) than between H. annuus and H. argophyllus (10 inverted segments, 8 translocated segments), consistent with their known phylogenetic relationships. Marker order was conserved across much of the genome, with 83 and 64% of the H. argophyllus and H. niveus ssp. tephrodes genomes, respectively, being syntenic with H. annuus. Population genomic analyses between H. annuus and H. argophyllus, which are sympatric across a portion of the natural range of H. annuus, revealed significantly elevated genetic structure in rearranged portions of the genome, indicating that such rearrangements are associated with restricted gene flow between these two species.
Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
Jessica G
JG
Barb
Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
John E
JE
Bowers
Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
Sebastien
S
Renaut
Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia 30602.
Juan I
JI
Rey
Center for Applied Genetic Technologies, University of Georgia, Athens, Georgia 30602.
Steven J
SJ
Knapp
Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
Loren H
LH
Rieseberg
Department of Plant Biology, University of Georgia, Athens, Georgia 30602 jmburke@uga.edu.
John M
JM
Burke
D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D019143:Evolution, Molecular; D008040:Genetic Linkage; D014644:Genetic Variation; D005828:Genetics, Population; D018745:Genome, Plant; D006368:Helianthus / Q000235:genetics*; D007178:Inbreeding; D026801:Synteny / Q000235:genetics
comparative mapping; gene flow; genome rearrangement; karyotypic evolution; reproductive isolation