Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: W41 - CONSOLIDATION AND EXPLOITATION OF THE EUROPEAN APPLE GENOME MAP
W41
CONSOLIDATION AND EXPLOITATION OF THE EUROPEAN APPLE GENOME MAP
KING, GRAHAM JOHN
Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, U.K.
The concerted efforts of researchers throughout Europe has resulted in construction of a reference linkage map for the Malus genome. This comprises 17 pairs of parental linkage groups, based on a segregating population of 160 individuals from the cross Prima x Fiesta. Due to the 'narrow' cross employed, between two commercial cultivars, there has been relatively slow progress in identification of polymorphic markers (isozyme, RFLP and RAPD). However, the markers are now readily applicable to a wide range of breeding material, and are being supplemented by transportable SSRs. Regions of the map around resistance loci are relatively well saturated, as a result of earlier bulked segregant strategies employed. Resistance genes (to scab, mildew and at least two aphids) have been tagged in a range of crosses, and markers are being developed to place these in the context of the reference map. Loci determining self-incompatibility, constitutive red tissue the compact-columnar habit have also been mapped. Where possible, markers flanking loci of high agronomic value are being converted into PCR-based assays for parental or progeny selection. A large amount of associated trait data has been accumulated from trials replicated in different countries and over several years. This is providing a rich resource with which to identify genetic components underlying variation for tree development and fruit quality. We are now starting to exploit the map by focusing on genes sequences which may determine aspects of fruit quality, such as fruit texture or acidity. The development of a database to manage the different aspects of genetic resources, trials, traits and marker loci is proving valuable in exploitation of these data, as well as providing a model for application in other crops. end.