Saturation of genomic regions conferring broomrape and ascochyta
blight resistance in faba bean (Vicia faba L.).
Gloria María García1, Ana María Torres1, Zlatko Šatović2, Belén Román1, Ramón Díaz3
1
Centro 'Alameda del Obispo' - IFAPA, Área de Mejora y Biotecnología, Córdoba, Spain
University of Zagreb, Faculty of Agriculture, Svetošimunska cesta 25, 10000 Zagreb, Croatia,
(e-mail: zsatovic@agr.hr)
3
Colegio de Postgraduados - Campus Puebla, C.P. 72760, Puebla, Pue., Mexico
2
Abstract
Broomrape (Orobanche crenata Forsk.) and ascochyta blight (caused by Ascochyta fabae
Speg.) resistance in faba bean (Vicia faba L.) are complex traits, difficult to manipulate
using conventional breeding procedures. The accurate identification of genomic locations
of individual quantitative trait loci (QTLs) controlling resistance is of utmost importance in
order to develop marker-assisted selection (MAS) programmes. Previous QTL mapping
studies in F2 as well as in recombinant inbred lines (RIL) population detected two QTLs
controlling broomrape resistance that were stable across generations and across
environments: Oc2 (linkage group VI.B) and Oc3 (LG II.A). Similarly, two QTLs
conferring resistance to Ascochyta fabae were identified in F2 population and further
validated in RILs: Af1 (LG III.A) and Af2 (LG II.A).
Bulked segregant analysis (BSA) based on previous QTL mapping information was
applied to saturate the targeted regions. Bulks fixed for alleles of the two markers flanking
four QTL regions were selected from the RIL population. More than seven hundred RAPD
primers were screened for polymorphism between the two bulks of each target region
revealing 31 putatively linked markers. Twenty-four out of 31 RAPD markers were
mapped to target linkage groups: 11 to LG VI.B (Oc2), 8 to LG II.A (Oc3 and Af2), and 5
to LG III.A (Af1). By inclusion of additional markers the average intermarker distance on
target linkage groups significantly decreased allowing more accurate determination of QTL
locations and effects.
Key words: Faba bean, Resistance breeding, Quantiative trait loci (QTLs), Bulk segregant
analysis (BSA), Saturation mapping