RESUMEN
Cytoplasmic male sterility (cms) in rye (Secale cereale L.), especially cytoplasma PAMPA, is used commercially in hybrid breeding programmes. The development of molecular markers that are tightly linked to the numerous genes coding for pollen fertility is expected to have great impact in the field. Morphological and cytological analyses of plants from a three-way cross C394: [(S67P/94 x S38/94) x CHD296] indicated the presence of at least several genes acting at different stages of pollen grain development, and proved the concurrence of both approaches in plant classification. The AFLP technique combined with the Bulk Segregant Analysis (BSA) were applied to identify DNA fragments linked to the genes of interest. All the 256 possible primer pair combinations based on the MseI and EcoRI restriction sites generated distinct band patterns allowing the identification of 31143 DNA fragments, visualised using the isotopic method. On average, any given primer combination generated 122 fragments. Among 1111 and 431 potential genetic markers respectively identified in the restorer form and the maternal lines, 775 and 295 were present in the F2 population. These numbers were then reduced to 109 and 51. The identified DNA fragments were tested on a limited segregating population, C394-F2, in order to eliminate false signals and to select markers for a future marker-assisted selection programme. Twenty-five markers were selected. Four of these markers were not identified via the BSA approach, indicating that if a highly polymorphic component is used for a cross, or a polygenic trait is studied, then the use of a limited population may be required.
Asunto(s)
Secale/genética , Cruzamiento , ADN de Plantas/genética , Genes de Plantas , Marcadores Genéticos , Hibridación Genética , Polen/genética , Polen/ultraestructura , Polimorfismo Genético , Secale/anatomía & histología , Selección GenéticaRESUMEN
Twenty-five AFLPs, previously linked to fertility restoration genes for the male-sterilizing PAMPA cytoplasm (cms-P) in a restricted rye population, were studied in an enlarged population of 120 plants. A strong association with the trait was verified for 19 of the markers. The recombination of these markers was tested and two linkage groups were identified: one consisting of six and the other of eight AFLPs. The remaining markers were segregated as independent loci. Using wheat-rye addition and substitution lines, the AFLPs were assigned to individual rye chromosomes. AFLP profiles of such lines were generated to identify the DNA fragments co-migrating with individual markers. This identified 1R and 3R as the two chromosomes corresponding to the linkage groups of eight and six markers, respectively. Mapping in a DS2 x RXL10 population linked four additional AFLPs to chromosome arms 1RS, 3RL, 4RL and 6RL. RAPD and SSR markers mapped in various populations and known to be located on the appropriate chromosomes did not disrupt the C394-F2 population into sterile and fertile phenotypes. It was concluded that the identified markers would reduce by one half the number of primer pair combinations needed for molecular breeding programs or for the selection of parental forms for rye hybrid crosses.