title: Comparative physical mapping links conservation of microsynteny to chromosome structure and recombination in grasses.
abstract: Nearly finished sequences for model organisms provide a foundation from which to explore genomic diversity among other taxonomic groups. We explore genome-wide microsynteny patterns between the rice sequence and two sorghum physical maps that integrate genetic markers, bacterial artificial chromosome (BAC) fingerprints, and BAC hybridization data. The sorghum maps largely tile a genomic component containing 41% of BACs but 80% of single-copy genes that shows conserved microsynteny with rice and partially tile a nonsyntenic component containing 46% of BACs but only 13% of single-copy genes. The remaining BACs are centromeric (4%) or unassigned (8%). The two genomic components correspond to cytologically discernible "euchromatin" and "heterochromatin." Gene and repetitive DNA distributions support this classification. Greater microcolinearity in recombinogenic (euchromatic) than nonrecombinogenic (heterochromatic) regions is consistent with the hypothesis that genomic rearrangements are usually deleterious, thus more likely to persist in nonrecombinogenic regions by virtue of Muller's ratchet. Interchromosomal centromeric rearrangements may have fostered diploidization of a polyploid cereal progenitor. Model plant sequences better guide studies of related genomes in recombinogenic than nonrecombinogenic regions. Bridging of 35 physical gaps in the rice sequence by sorghum BAC contigs illustrates reciprocal benefits of comparative approaches that extend at least across the cereals and perhaps beyond.
authors.affiliation: Plant Genome Mapping Laboratory, University of Georgia, Athens, GA 30602, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Bowers
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Arias
authors.forename: Rochelle
authors.initials: R
authors.lastname: Asher
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Avise
authors.forename: Robert T
authors.initials: RT
authors.lastname: Ball
authors.forename: Gene A
authors.initials: GA
authors.lastname: Brewer
authors.forename: Ryan W
authors.initials: RW
authors.lastname: Buss
authors.forename: Amy H
authors.initials: AH
authors.lastname: Chen
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Edwards
authors.forename: James C
authors.initials: JC
authors.lastname: Estill
authors.forename: Heather E
authors.initials: HE
authors.lastname: Exum
authors.forename: Valorie H
authors.initials: VH
authors.lastname: Goff
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Herrick
authors.forename: Cassie L James
authors.initials: CL
authors.lastname: Steele
authors.forename: Santhosh
authors.initials: S
authors.lastname: Karunakaran
authors.forename: Gmerice K
authors.initials: GK
authors.lastname: Lafayette
authors.forename: Cornelia
authors.initials: C
authors.lastname: Lemke
authors.forename: Barry S
authors.initials: BS
authors.lastname: Marler
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Masters
authors.forename: Joana M
authors.initials: JM
authors.lastname: McMillan
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Nelson
authors.forename: Graham A
authors.initials: GA
authors.lastname: Newsome
authors.forename: Chike C
authors.initials: CC
authors.lastname: Nwakanma
authors.forename: Rosana N
authors.initials: RN
authors.lastname: Odeh
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Phelps
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Rarick
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Rogers
authors.forename: Sean P
authors.initials: SP
authors.lastname: Ryan
authors.forename: Keimun A
authors.initials: KA
authors.lastname: Slaughter
authors.forename: Carol A
authors.initials: CA
authors.lastname: Soderlund
authors.forename: Haibao
authors.initials: H
authors.lastname: Tang
authors.forename: Rod A
authors.initials: RA
authors.lastname: Wing
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Paterson
mesh_terms: D001483:Base Sequence; D022004:Chromosome Structures; D022041:Euchromatin; D018745:Genome, Plant; D006570:Heterochromatin; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D020161:Physical Chromosome Mapping / Q000379:methods*; D006109:Poaceae / Q000235:genetics*; D011995:Recombination, Genetic; D045868:Sorghum / Q000235:genetics; D026801:Synteny
chemical_list: D022041:Euchromatin; D006570:Heterochromatin