Construction of a BAC library and its application to the identification of simple sequence repeats in peach [Prunus persica (L.)Batsch.]

The Rosaceae contains many economically important crop species, but their genomes are not well characterized, and comparative genetic mapping lags well behind that of other families. To facilitate genome comparisons and gene discovery in the Rosaceae, we have begun the development of genomic resources for peach as the model genome for this family. First, we developed a simplified, cost-effective method for constructing BAC libraries, particularly appropriate for plant species of relatively minor economic importance. Second, we used the library to investigate the abundance and local distribution of simple sequence repeats (SSRs)in peach. Our results indicate that microsatellite loci are locally much more highly abundant than previously estimated, and BAC sequencing results suggest that microsatellite repeats are not randomly distributed within gene-containing regions of the peach genome. This makes it relatively easy to identify SSRs in peach by hybridization to BAC clones, and even by random sequencing of BAC clones, not known a priori to contain SSRs.