RESUMO
Using the technique of amplified restriction fragment polymorphism (AFLP) analysis, and bulked segregant pools from F2 progeny of the cross Lycopersicon esculentum (Cf9) x L. pennellii, approximately 42,000 AFLP loci for tight linkage to the tomato Cf-9 gene for resistance to Cladosporium fulvum have been screened. Analysis of F2 recombinants identified three markers which co-segregated with Cf-9. The Cf-9 gene has recently been isolated by transposon tagging using the maize transposon Dissociation (Ds). Analysis of plasmid clones containing Cf-9 shows that two of these markers are located on opposite sides of the gene separated by 15.5 kbp of intervening DNA. AFLP analysis provides a rapid and efficient technique for detecting large numbers of DNA markers and should expedite plant gene isolation by positional cloning and the construction of high-density molecular linkage maps of plant genomes.
Assuntos
Cladosporium/patogenicidade , Genes de Plantas , Marcadores Genéticos , Doenças das Plantas/genética , Solanum lycopersicum/genética , Sequência de Bases , Mapeamento Cromossômico , Cruzamentos Genéticos , Amplificação de Genes , Ligação Genética , Biblioteca Genômica , Imunidade Inata/genética , Solanum lycopersicum/microbiologia , Meiose , Dados de Sequência Molecular , Polimorfismo de Fragmento de Restrição , Recombinação Genética , Especificidade da EspécieRESUMO
Four different populations segregating for one of the two closely linked (possibly allelic) tomato disease resistance genes to the fungusCladosporium fulvum,Cf-4 andCf-9, were generated and analysed for recombination frequencies between theCf-genes and restriction fragment length polymorphism (RFLP) loci. The population consisting of F2 progeny from the interspecific crossLycopersicon esculentum carryingCf-9 ×L. pennellii was identified as the most useful for RFLP mapping of theCf-4/9 locus and an RFLP map around this locus was constructed mainly using this population. The two closest markers identified were CP46, 2.6 cM distal, and a group of 11 markers including TG236, 3.7 cM proximal toCf-4/9. A polymerase chain reaction (PCR)-based procedure for the rapid identification of recombination events between these two markers was developed. The regions of foreign DNA introgression surroundingCf-4 andCf-9 in near-isogenic lines were delimited.
