F2-3
The genomic DNA from each sample was digested by EcoRI and an adapter (P1) was ligated to the fragmentĄŻs compatible ends. The adapter-ligated fragments were subsequently pooled, randomly sheared, and size-selected. The fragments were then ligated to a second adapter (P2), a Y adapter that has divergent ends22. Finally, the fragments from the 18 cycles of PCR amplification of 200 bp to 400 bp were collected for the purpose of constructing a library.