DEVELOPMENT OF A PHYSICAL AND A TRANSCRIPT MAP FOR PEACH: A MODEL TREE SPECIES FOR ROSACEAE

¹ Department of Genetics, Biochemistry and Life Science Studies, Clemson University, Clemson, SC, 29634, USA

² Horticulture Department, Clemson University, Clemson, SC, 29634,USA

³ Department of Plant Pathology, North Carolina State University, Raleigh, NC, 27695, USA

⁴ Department of Plant Breeding, Institut de Recerga I Tecnologia Agroalimentaries, Cabrilis, Spain

⁵ Department of Pomology, University of California Davis, Davis, CA 95616, USA

Peach has become a model species within the Rosaceae because several features make it favorable for genetic studies. The small genome size, the relatively short generation time for fruit trees and the diploid genome facilitate studies in peach compared to any of the polyploid species of this family. However, progress in identifying candidate genes controlling many important fruit tree characters is hampered by the lack of a comprehensive transcript and physical map. Therefore, we have initiated peach projects with the goal of developing an extensive peach EST database and of constructing a physical map for peach. Using core markers from the general Prunus genetic map, BAC clones were anchored on the map providing a framework for construction of a physical and a transcript map. We generated 9984 high-quality ESTs, assembled and annotated them to define the first putative unigene set of peach consisting of 3842 ESTs. To develop a transcript map, 1304 ESTs were hybridized against the peach BAC library. This immediately localized 11.2% of the ESTs on the genetic map. In addition, we have fingerprinted more than 15,000 BAC clones of a first BAC library (Nemared) and 5000 clones of a second library (Lovell). Restriction fragment assignment was performed using IMAGE software and contigs were assembled with FPC version 4.7. Using the BAC fingerprints of the Nemared genomic library, we have combined 4507 BAC clones into 938 contigs, 5712 BAC clones remained singletons. The data were built into a regularly updated Genome Database for Rosaceae (GDR), available at http://www.genome.clemson.edu/gdr/.