Schematic representation of conserved DNA and gene family based markers. Color boxes represent exons and solid black lines introns, while intergenic regions are indicated by dashed lines. Red, green and black arrows are primers used for amplification in each technique. a) The cytochrome P450 Based Analogue (PBA) marker system is based on the amplification of Cyt P450 regions in plants with universal primers designed in CYP or heme-binding sites. b) Representation of the transcribed region of a typical plant β-tubulin gene, showing specific amplification with TBP (red arrows), cTBP (black arrows) and hTBP (green arrows). c) Outline of intron-targeting markers with primers flanking the exon regions. A similar system can be applied to methods using conserved DNA-Derived Polymorphism (CDDP).