ISHS Acta Horticulturae 814: XII EUCARPIA Symposium on Fruit Breeding and Genetics
"FAST-BREEDING" IN APPLE: A STRATEGY TO ACCELERATE INTROGRESSION OF NEW TRAITS INTO ELITE GERMPLASM |
| Authors: | R.K. Volz, E. Rikkerink, P. Austin, T. Lawrence, V.G.M. Bus |
| Keywords: | whole genome selection, microsatellite markers, fruit quality, flowering, juvevility |
| Abstract:
Introgression of novel fruit traits and new resistances from ‘wild’ germplasm into elite material is an important breeding strategy for the HortResearch apple-breeding programme. Several generations of backcrossing are usually required before parental material suitable for cultivar breeding is available. We have developed a “fast breeding” approach to accelerate this process, which aims to reduce both the number of generations and the generation times. A set of molecular markers covering the whole genome has been developed and these are screened across a progeny array to identify seedlings with the desired new trait as well as high proportions of genome inherited from the high quality grandparent(s) and low proportions of genome of the low quality ancestor(s). The elite seedlings are then grown on their own roots in controlled environment rooms to advance flowering within two years of crossing, from which a further introgression cycle can be repeated. We report on initial results using a ‘Royal Gala’ x A689-24 family segregating for the Pl2 powdery mildew resistance gene derived from the crabapple ancestor Malus zumi and alleles from higher quality Malus x domestica ancestors. Since marker-based whole genome selection can be applied to select for differing contributions of the grandparental genomes, the theoretical limits of such selection pressure were assessed by estimating the contribution of each grandparent to each progeny. Variability within the progeny for ancestral genomic contributions and some preliminary results associating this variability with fruit phenotype are discussed. We also report on the progress to date of the application of accelerated flowering. | |
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