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- Molecular characterization of Phaseolus vulgaris L. genotypes included in Bulgarian collection by ISSR and AFLP (TM) analysesPublication . Svetleva, D.; Pereira, G.; Carlier, Jorge; Cabrita, L.; Leitão, J. M.; Genchev, D.Seventy-eight (33 Bulgarian and 45 foreign) common bean (Phaseolus vulgaris L.) genotypes included in Bulgarian collection were screened for ISSR (Inter Simple Sequence Repeats) and AFLP (TM) (Amplified Fragment Length Polymorphism) markers. ISSR analysis was performed with 13 primers, and 55 (36.7%) out of the 150 bands observed were polymorphic. One hundred and sixty-four AFLP (TM) fragments were obtained with three primer combinations, of which 54 (32.9%) were polymorphic. UPGMA (Unweighted Pair Group Method Arithmetic Averages) analysis was performed using DICE coefficient and dendrograms were constructed using either the data from each method (ISSR and AFLP (TM)) separately or combined in a single joint matrix. Despite some genetic heterogeneity observed in both pools (Middle American origin: M and Andean origin: A) the genotypes were separated in to main groups: one gathering genotypes mainly from pool M and the other more genotypes from pool A. Moreover, Bulgarian genotypes were spread over the two groups suggesting that they are not subject to genetic erosion and that the Phaseolus genetic diversity is conserved. (c) 2006 Elsevier B.V. All rights reserved.
- Mapping of a locus for adult plant resistance to downy mildew in broccoli (Brassica oleracea convar. italica)Publication . Farinho, M.; Coelho, P.; Carlier, Jorge; Svetleva, D.; Monteiro, A.; Leitão, J. M.The identification of the gene Pp523, conferring downy mildew resistance to adult plants of broccoli (Brassica oleracea convar. italica), led to the construction of a genetic map that included this resistance locus, 301 amplified fragment length polymorphisms, 55 random amplified polymorphic DNAs, 46 inter-simple sequence repeats, three simple sequence repeats, four other PCR markers and a flower colour locus, all gathered into nine major linkage groups. Nineteen additional molecular markers were clustered into one group of four markers, one group of three markers and six pairs of markers. The map spans over 731.9 cM, corresponding to 89.5% of the 818 cM estimated to be the total genome length. A significant number of the mapped markers, 19.3%, showed distorted segregation. The average distance between mapped adjacent markers is 1.64 cM, which places this map among the densest published to date for this species. Using bulked segregant analysis, we identified a group of molecular markers flanking and closely linked in coupling to the resistance gene and included these in the map. Two markers linked in coupling, OPK17_980 and AT.CTA_133/134, are located at 3.1 cM and 3.6 cM, respectively, at each side from the resistance gene. These markers can be used for marker-assisted selection in breeding programs aiming at the introgression of this gene in susceptible B. oleracea genotypes. The fine mapping of the genomic region surrounding the Pp523 resistance gene is currently being carried out, a basic condition for its isolation via positional cloning.
- Identification of RAPD markers linked to the Fin and P loci in Phaseolus vulgaris L.Publication . Apostolova, E.; Svetleva, D.; Carlier, Jorge; Leitão, JoséBulked segregant analysis was used to identify random amplified polymorphic DNA RAPD markers linked to the genes for indeterminate growth habit (Fin) and seed color (P) in common bean (Phaseolus vulgaris L.) using an F2 population derived from the cross A 195 × Kristal 137. The variety A 195 is characterized by determinate growth habit and brown colored seeds, while Kristal 137 exhibits indeterminate growth habit and white colored seeds. Among the 140 RAPD primers used to discriminate between two parental genotypes and between two bulks of DNA, respectively, from determinate and indeterminate plants, only 64 (45.71%) amplified polymorphic markers. Nineteen primers amplified clear polymorphic bands and were further tested among 100 F 2 plants. The analysis of the genetic linkage between analyzed molecular markers and the loci for indeterminate growth habit and seed color was performed using the program Join Map 3.0. The logarithm of odds (LOD) of 8.0 and 10 were used as thresholds for linkage grouping, respectively of locus Fin and locus P. One RAPD marker, AA18-600-P1, was found linked to the Fin locus that determines plant habit type and mapped at 17.6 cM apart from it (rec. freq. = 0.162). Five RAPD markers were found linked to the P locus, with distances to this locus varying from 4.1 cM (marker AB18 1500-P2, rec. freq.= 0.034) to 42.6 cM (marker Q03700-P1).