Strategy for identification of BAC clones containing genes of interest. Genes of interest or partial Oncidium sequences were used for the BAC library screening. Primers were designed and genomic DNA PCR was performed before the screening. The products were sequenced to confirm results. After superpooling, plate PCR, row PCR and spot PCR, BAC clones containing genes of interest were identified. Black box, negative control; white box, genome DNA positive control with genomic DNA; green box, superpool control; red box, plate control; blue box, row control; yellow box, identified clone.