Optimization of AFLP fingerprinting of organisms with a large-sized genome:: a study on Alstroemeria spp.

The recently introduced PCR-based DNA fingerprinting technique AFLP (amplified fragment length polymorphism) allows the selective amplification of subsets of genomic restriction fragments. AFLP has been used for multiple purposes such as the construction of linkage maps, marker saturation at specific genomic regions, analysis of genetic diversity and molecular phylogeny and cultivar identification. AFLP can be tailored by varying the number of selective nucleotides added to core primers and can allow accurate amplification, even in complex template mixtures generated from plant species with very large genomes. In this study Alstroemeria, a plant species with a very large genome, was tested for adapting the AFLP protocol. The results indicated that the estimated number of amplification products was close to the observed number when eight selective nucleotides were used but that seven selective nucleotides did not increase the number of amplification products fourfold. However, we found reproducibility in both +7 and +8 fingerprints. Various distributions of selective nucleotides over the various rounds of preamplifications were tested. Preamplification with four selective nucleotides followed by final amplification with eight selective nucleotides produced clear and reproducible AFLP patterns. The effects of GC content of primers and multiple preamplification steps were also discussed.