ISHS Acta Horticulturae 528: VII International Symposium on Grapevine Genetics and Breeding
QTL ANALYSIS OF DISEASE RESISTANCE IN INTERSPECIFIC HYBRID GRAPES |
| Authors: | M.A. Dalbó, N.F. Weeden, B.I. Reisch |
| Keywords: | Molecular markers, RAPD, Vitis, Uncinula necator, Guignardia bidwellii |
| DOI: | 10.17660/ActaHortic.2000.528.29 |
| Abstract:
Most commercial grape (Vitis vinifera) cultivars are susceptible to several fungal diseases but resistance is present in related species. Molecular markers associated with resistance genes can be useful in breeding resistant cultivars. We studied the inheritance of powdery mildew (PM) and black rot (BR) resistance in the cross ‘Horizon’ (complex interspecific hybrid) x Illinois 547–1 (V. rupestris x V. cinerea). A genetic map based mostly on RAPD markers was constructed for each parent. Data from five years of observation of this population for powdery mildew resistance was used for QTL (Quantitative Trait Loci) analysis. A major QTL was found in Illinois 547–1, the resistant parent. A single marker (CS25b) associated with this QTL accounted for approximately 41% of the phenotypic variation. The same marker was present in V. cinerea B9, one of the parents of Ill. 547–1 and the likely source of resistance. Two other regions in the Horizon map were associated with resistance but with less intensity. Specific markers (e.g. CAPS) developed for the CS25b locus were also useful to separate resistant and susceptible individuals in the progenies of other crosses where the same source of resistance was used. Interestingly, resistance to PM and BR was correlated in the Horizon x Ill. 547–1 progeny. The same map locations associated to PM resistance were also associated with BR resistance but to different degrees. The results show that resistance to PM and BR may be polygenically inherited but major genes or gene clusters are involved. | |
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