Application of retrotransposon-based Inter-SINE Amplified Polymorphism (ISAP) markers for the differentiation of common poplar genotypes
On the basis of retrotransposon-insertion polymorphisms, molecular markers were developed for the identification and differentiation of poplar (<i>Populus</i> spp.) genotypes. For this purpose, short interspersed nuclear elements (SINEs) in the genome sequence of <i>Populus tremula</i> were identified and assigned to different SINE-families. For families with high copy number and high identity values, primers were derived to amplify Inter- SINE Amplified Polymorphisms (ISAPs) with polymerase chain reaction (PCR). The resulting fragments produce genotype-specific fingerprints. This molecular approach utilizes standard laboratory equipment and is therefore easy to use for the verification of plant material. We demonstrate the functionality of three distinct ISAP primer combinations by comparison to ten simple sequence repeat (SSR) markers to differentiate 23 poplar genotypes. Already by using a single ISAP primer combination all genotypes can be clearly discriminated. Furthermore, the cluster analysis based on three primer combinations divides clones according to their genetic background into two subclusters (by a bootstrap value of 98). Our results clearly demonstrate the usability of ISAP markers to differentiate genotypes and trace progenies of poplar trees.