title: Comparative mapping and rapid karyotypic evolution in the genus helianthus.
abstract: Comparative genetic linkage maps provide a powerful tool for the study of karyotypic evolution. We constructed a joint SSR/RAPD genetic linkage map of the Helianthus petiolaris genome and used it, along with an integrated SSR genetic linkage map derived from four independent H. annuus mapping populations, to examine the evolution of genome structure between these two annual sunflower species. The results of this work indicate the presence of 27 colinear segments resulting from a minimum of eight translocations and three inversions. These 11 rearrangements are more than previously suspected on the basis of either cytological or genetic map-based analyses. Taken together, these rearrangements required a minimum of 20 chromosomal breakages/fusions. On the basis of estimates of the time since divergence of these two species (750,000-1,000,000 years), this translates into an estimated rate of 5.5-7.3 chromosomal rearrangements per million years of evolution, the highest rate reported for any taxonomic group to date.
authors.affiliation: Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, USA. john.m.burke@vanderbilt.edu
authors.forename: John M
authors.initials: JM
authors.lastname: Burke
authors.forename: Zhao
authors.initials: Z
authors.lastname: Lai
authors.forename: Marzia
authors.initials: M
authors.lastname: Salmaso
authors.forename: Takuya
authors.initials: T
authors.lastname: Nakazato
authors.forename: Shunxue
authors.initials: S
authors.lastname: Tang
authors.forename: Adam
authors.initials: A
authors.lastname: Heesacker
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Knapp
authors.forename: Loren H
authors.initials: LH
authors.lastname: Rieseberg
mesh_terms: D005075:Biological Evolution; D002874:Chromosome Mapping / Q000379:methods*; D002875:Chromosomes / Q000648:ultrastructure; D019143:Evolution, Molecular; D017343:Genes, Plant; D008040:Genetic Linkage; D005821:Genetic Techniques; D018745:Genome, Plant; D006368:Helianthus / Q000235:genetics*; D007621:Karyotyping; D008957:Models, Genetic; D013045:Species Specificity; D013997:Time Factors; D014178:Translocation, Genetic