Cloning of the BnAP2 gene with the aid of the comparative map. A) Localization of the BnAP2 gene and its allele-specific marker on LG A1. The red arrow on the left panel marks the AP2 position as predicted in conserved block U. The right panel is a reconstructed LG A1 with the BnAP2 allele-specific marker. B) PCR products amplified from the parental lines and their F1. The PCR products are separated by electrophoresis in 1.0% agarose gels and stained with ethidium bromide. C) Sequence difference of the BnAP2 gene sequences between the two parental lines. There is a 290bp insertion in SW Hickory.