Identification and mapping of polymorphisms in cereals based on the polymerase chain reaction

The polymerase chain reaction (PCR) can be used to detect polymorphisms in the length of amplified sequences between the annealing sites of two synthetic DNA primers. When the distance varies between two individuals then the banding pattern generated by the PCR reaction is essentially a genetic polymorphism and can be mapped in the same way as other genetic markers. This procedure has been used in a number of eukaryotes. Here we report the use of PCR to detect genetic polymorphisms in cereals. Known gene sequences can be used to design primers and detect polymorphic PCR products. This is demonstrated with primers to the α-amylase gene family. A second approach is to use semi-random primers to target diverse regions of the genome. For this purpose the consensus sequences at the intron-exon splice junctions were used. The targeting of the intronexon splice junctions in conjunction with primers of random and defined sequences, such as α-amylase, provides a source of extensive variation in PCR products. These polymorphisms can be mapped as standard genetic markers.