Reproducibility testing of RAPD and SSR markers in Tomato

Large no of PCR-based techniques can be used to detect polymorphisms in plants. For their wide-scale usage in germplasm characterization and breeding it is important that these marker technologies can be exchanged between laboratories, which in turn require that they can be standardized to yield reproducible results, so that direct collation and comparison of the data are possible. This article describes a network experiment involving screening of 60 RAPD primers and was used to confirm the reproducibility. Every experiment was performed 50 times by 10 candidates in which the reproducibility of two popular molecular marker techniques was examined: random-amplified fragment length polymorphism (RAPD), and sequence-tagged micro satellites (SSR). For each technique, an optimal system was chosen, which had been standardized and routinely used by one individual. This system (genetic screening package) was distributed to different candidates in the laboratory and the results obtained were compared with those of the original generator or sender. Different experiences were gained in this exchange experiment with the different techniques. RAPDs proved difficult to reproduce. Whilst SSR alleles were amplified by all candidates, but small differences in their sizing were obtained