ISHS Acta Horticulturae 592: V International Peach Symposium
INTROGRESSION OF A POLYGENIC RESISTANCE TO POWDERY MILDEW FROM A WILD SPECIES PRUNUS DAVIDIANA INTO PEACH (PRUNUS PERSICA (L.) BATSCH), A CASE STUDY OF MARKER ASSISTED SELECTION IN FRUIT TREE |
| Authors: | M. Foulongne, T. Pascal, F. Pfeiffer, J. Kervella |
| Keywords: | QTL validation, Sphaerotheca pannosa var. persicae, molecular markers, breeding program |
| Abstract:
In order to improve peach resistance to powdery mildew, a backcross breeding scheme has been carried on, from a cross between the peach cultivar ‘Summergrand’, susceptible to powdery mildew and a clone (P1908) of Prunus davidiana, a wild species closely related to Prunus persica, which has a polygenic resistance to this pathogen (Pascal et al., 1997). One hybrid from the progeny obtained (called SD40) was selected for resistance to powdery mildew, and used as parent for a backcross with ‘Summergrand’. The BC1 progeny was scored for resistance to powdery mildew. Mixtures were constituted from pollen of all resistant and all susceptible hybrids of this BC1 progeny and used to produce pseudo-BC2 progenies with ‘Zephyr’, another commercial cultivar. Meanwhile, a study of the genetic basis of the resistance was undertaken: a genetic map of P1908 was performed on 77 hybrids of the SD progeny. Several QTLs were detected (Dirlewanger et al., 1996). Further search, for possible homozygous resistance genes of P1908, was done using SD40 selfed progeny. The detection of possible recessive genes, that could not yet be exploited in the breeding process undertaken, would be of major importance. When the search for resistance QTLs was achieved, some pseudo-BC2 progenies were genotyped for markers closed to each of the QTLs. In this way, we were able to validate some QTLs previously detected. Furthermore, in order to assess the efficiency of the differential selection, we analysed the frequencies of P. davidiana alleles in the BC2 progenies. These results should allow us to efficiently design further crosses for pyramiding all the resistance genes in a single cultivar. | |
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