title: Construction of a high-resolution genetic map and YAC-contigs in the tomato Tm-2a region.
abstract: With the ultimate goal of cloning the Tobacco Mosaic Virus (TMV) resistance gene Tm-2a from tomato by means of positional cloning, a high-resolution map of a 4.3-cM region surrounding the Tm-2a gene has been constructed. In total, 13 RFLP and RAPD markers were mapped in close proximity to Tm-2a using 2112 individuals from an intraspecific Lycopersicon peruvianum backcross. The closest flanking markers were separated from Tm-2a by 0.05 cM on each side. Only one marker, the cDNA clone R12, co-segregated with Tm-2a. In order to physically cover the Tm-2a region, R12 and the flanking DNA marker TG207 were used to select homologous YAC clones. To-date, two YAC-contigs spanning approximately 340 kb and 360 kb have been constructed. The data obtained from these experiments indicate that recombination around the centromere of chromosome 9 is extremely suppressed.
authors.affiliation: Department of Plant Breeding and Biometry, 252 Emerson Hall, Cornell University, 14853, Ithaca, NY, USA.
authors.forename: K
authors.initials: K
authors.lastname: Pillen
authors.forename: M W
authors.initials: MW
authors.lastname: Ganal
authors.forename: S D
authors.initials: SD
authors.lastname: Tanksley