THE PEACH: A MODEL GENOME FOR THE FAMILY ROSACEAE?

¹ Department of Biological Sciences, Clemson University, Clemson, South Carolina, 29634-1903 USA

² Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, USA

Traditionally, the Rosaceae, a diverse and important plant family, is divided into four well-defined subfamilies. One subfamily, the Prunoideae, characterized by species that produce drupes as fruit, contains several important fruit tree species (i.e., almond, apricot, cherry, peach and plum). Peach is considered the best genetically characterized species in this subfamily and one of the best genetically characterized fruit tree species. With the application of DNA marker technologies to the problem of developing genetic resources in trees, peach has distinct advantages making it suitable as a model genetic resource for genomic studies in deciduous trees and for the family Rosaceae. Peach has a relatively short juvenility period (2-3 years) compared to most other fruit tree species, such as apple, pear, and citrus, that have juvenile phases ranging from 6-10 years. While some Prunus species such as cultivated plums and sour cherries are polyploid, peach is a diploid species with n = 8. Peach has a comparatively small genome size. Using flow cytometry, we estimate it to be 5.9 x 108 bp or 0.61 pg/diploid nucleus, only about twice the value for Arabidopsis thaliana. We have established a Rosaceae genome consortium which has as one of its primary goals the establishment of the peach genome as a suitable molecular genetic model for Rosaceae and other deciduous trees. We present here our initial efforts to demonstrate the potential for the peach genome to serve as a model for the study of genome evolution in Rosaceae and for identification and cloning of important genes.