title: Comparative transmission genetics of introgressed chromatin in Gossypium (cotton) polyploids.
abstract: Introgression is widely acknowledged as a potential source of valuable genetic variation, and growing effort is being invested in analysis of interspecific crosses conferring transgressive variation. Experimental backcross populations provide an opportunity to study transmission genetics following interspecific hybridization, identifying opportunities and constraints to introgressive crop improvement. The evolutionary consequences of introgression have been addressed at the theoretical level, however, issues related to levels and patterns of introgression among (plant) species remain inadequately explored, including such factors as polyploidization, subgenome interaction inhabiting a common nucleus, and the genomic distribution and linkage relationships of introgressant alleles.
  
  
  
  We analyze introgression into the polyploid Gossypium hirsutum (upland cotton) from its sister G. tomentosum and compare the level and pattern with that of G. barbadense representing a different clade tracing to the same polyploidization.
  
  
  
  Across the genome, recurrent backcrossing to Gossypium hirsutum yielded only one-third of the expected average frequency of the G. tomentosum allele, although one unusual region showed preferential introgression. Although a similar rate of introgression is found in the two subgenomes of polyploid (AtDt) G. hirsutum, a preponderance of multilocus interactions were largely within the Dt subgenome.
  
  
  
  Skewed G. tomentosum chromatin transmission is polymorphic among two elite G. hirsutum genotypes, which suggests that genetic background may profoundly affect introgression of particular chromosomal regions. Only limited correspondence is found between G. hirsutum chromosomal regions that are intolerant to introgression from the two species, G. barbadense and G. tomentosum, concentrated near possible inversion polymorphisms. Complex transmission of introgressed chromatin highlights the challenges to utilization of exotic germplasm in crop improvement.
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA, USA Division of Crop Improvement, Central Institute for Cotton Research, Nagpur, India.
authors.forename: Vijay N
authors.initials: VN
authors.lastname: Waghmare
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA, USA.
authors.forename: Junkang
authors.initials: J
authors.lastname: Rong
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA, USA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Rogers
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Bowers
authors.affiliation: Department of Crop and Soil Sciences, University of Georgia, Tifton, GA, USA.
authors.forename: Peng W
authors.initials: PW
authors.lastname: Chee
authors.affiliation: Texas A&M Research and Extension Center, Lubbock, TX, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Gannaway
authors.affiliation: Agricultural Research Station, University of Agricultural Sciences, Dharwad, Karnataka, India.
authors.forename: Ishwarappa
authors.initials: I
authors.lastname: Katageri
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA, USA paterson@plantbio.uga.edu.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Paterson
mesh_terms: D000483:Alleles; D002843:Chromatin / Q000378:metabolism; D020090:Chromosome Segregation / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D003433:Crosses, Genetic; D056426:Genetic Loci; D018745:Genome, Plant; D005838:Genotype; D003368:Gossypium / Q000235:genetics*; D007178:Inbreeding; D011123:Polyploidy
chemical_list: D002843:Chromatin
keywords: DNA markers; Epistasis; cotton; hybrid incompatibility; segregation distortion