Construction of a minimum tiling path of BAC clones covering the Sharka resistance region in apricot

Sharka is a devastating disease in stone fruit species caused by the Plum pox virus (PPV). Unlike other plant pathogens, PPV cannot be directly controlled by chemical sprays. Alternative approaches include the control of insect vectors and the use of pathogen-resistant cultivars. This work is aimed at developing new tools to understand the genetic control of resistance. A BAC library, covering about 10× the 'Lito' haploid genome, was used in order to identify candidate genes for Sharka resistance in apricot. SSRs markers covering the linkage group 1 of 'Lito', where resistance is located, were used for a preliminary screening of the BAC library. In a second step the screening was focused in a region between 6 and 8.5 Mbp (on the reference peach genome), that was covered by more than 50 new markers developed on both 'Lito' re-sequenced genome and sequenced BAC ends. Several BAC clones from both the resistant and susceptible chromosomes were identified (17 and 18 clones, respectively) in order to obtain the minimum tiling path covering the whole resistant and susceptible chromosome regions. The BAC clones sequencing by Illumina and assembly is in progress. The new markers developed in this work could be used to speed up the selection process in apricot breeding programs.