Construction and characterization of a bacterial artificial chromosome library from chili pepper

A library of the bacterial artificial chromosome (BAC) that consisted of a total of 78,336 clones with an average insert size of 80 kb was constructed from Capsicum annuum, 'CM334', which is resistant to Phytophthora capsici and PVY. Based on a haploid genome size of pepper of 2,702 Mbp/C, the BAC l ibrary was estimated to contain approximately three genome equivalents and represented at least 90% of the pepper genome. In order to determine the pe rcentage of BAC clones that contained mitochondrial DNAs, the entire librar y was screened with probes of chili pepper mitochondrial DNAs. The result s howed that only twenty-five clones, which is 0.03% of the total BAC clones, were hybridized to mitochondrial gene probes. This indicates that the libr ary is comprised predominantly of the nuclear sequences. The library was al so tested for isolating specific clones by screening with a few known genes from the chili pepper, phytoene synthase gene, and two MADS genes-HpMADS1 and HpMADS3. The result showed that the three clones for phytoene synthase and the two clones for each MADS gene were positively hybridized to the spe cific probes. This indicates that the library is highly reliable and repres ents a resource for initiating map-based cloning and contig mapping in chil i pepper.