Genomic DNA was digested with NdeI and BglII and ligated with adaptors. The ligation products were purified using AMPure XP kit (Beckman Coulter) and were amplified by PCR. The PCR products from multiple samples were pooled, and the pooled DNA fragments were concentrated using AMPure XP kit. For size selection, E-gel SizeSelect (LifeTechnologies) was used, and approximately 350 bp fragments were retrieved and purified.