title: Tyramide-FISH mapping of single genes for development of an integrated recombination and cytogenetic map of chromosome 5 of Allium cepa.
abstract: Chromosome 5 of onion carries major quantitative trait loci (QTL) that control dry-matter content, pungency and storability of bulbs, amounts and types of epicuticular waxes, and resistances to abiotic factors, all of which are of interest to breeders. SNPs, SSRs, and RFLPs in expressed regions of the onion genome have been genetically mapped, and we used these clones and sequences from the NCBI database to develop DNA probes for in situ hybridization to integrate the genetic and physical maps of onion chromosome 5. We produced genomic amplicons from expressed regions of the onion genome that carried both exons and introns in order to increase the hybridization specificity of the probes and to enlarge the target DNA sizes. Tyramide-FISH technique was used to increase the detection sensitivity of relatively short target DNA regions, which range from 950 to 2100 bp. Through the integration of genetic and chromosomal maps, we were able to estimate the distribution of recombination events along onion chromosome 5. We demonstrated the efficiency of chromosomal in situ mapping of exon-intron genomic clones for the extremely large genome of onion.
authors.affiliation: a Center of Molecular Biotechnology, Russian State Agrarian University - MTAA, Moscow 127550, Russia.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Romanov
authors.affiliation: a Center of Molecular Biotechnology, Russian State Agrarian University - MTAA, Moscow 127550, Russia.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Divashuk
authors.affiliation: b USDA-ARS and Department of Horticulture, University of Wisconsin, Madison, WI 53706 USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Havey
authors.affiliation: a Center of Molecular Biotechnology, Russian State Agrarian University - MTAA, Moscow 127550, Russia.
authors.forename: Ludmila
authors.initials: L
authors.lastname: Khrustaleva
mesh_terms: D002874:Chromosome Mapping / Q000379:methods; D032461:Chromosomes, Plant; D008040:Genetic Linkage; D005819:Genetic Markers; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D019697:Onions / Q000235:genetics*; D040641:Quantitative Trait Loci
chemical_list: D005819:Genetic Markers
keywords: Allium cepa; EST; Tyramide-FISH; chromosome; recombinaison; recombination