Valuation of genetic diversity of tomato (Solanum lycopersicum L.) based on the comparison of ISSR and SSR marker efficiency

This study was conducted to evaluate the genetic diversity of tomato accessions selected from the core collection of National Plant Gene Bank of Iran (NPGBI) based on a comparative assessment of SSR and ISSR markers. Genetic diversity of species and cultivars is necessary to increase productivity and production, and if diversity is reduced, species and cultivars are in danger of extinction. Due to the importance of tomato as the second most consumed crop among vegetables, it is necessary to study it. Other objectives of this study are to compare the performance of SSR and ISSR markers in differentiating tomato genotypes and to find primers with the highest polymorphism.

In this study, genetic diversity among and within tomato accessions collected from 8 geographic regions of Iran and 22 countries from the world were evaluated using 13 ISSR and 5 SSR primers.

The number of polymorphic alleles and the average of resolving power and marker index were related to the ISSR marker. However, the highest values of PIC for studied markers were obtained in the SSR primers. The molecular analysis of variance showed that both markers were suitable for the evaluation of diversity among species. Also, genetic diversity among the species was higher than within the species. The highest values of genetic diversity features were obtained in SSR primers. The lowest parameters were observed in the S. lycopersicum cherry in comparison to S. lycopersicum esculentum. In the cluster analysis, tomato accessions were distributed into four groups. PCoA was obtained for a more accurate explanation of the grouped accessions. These results indicated that SSR primers have had more tangible efficiency in showing the genetic diversity between Iranian and S. lycopersicum Cherry populations, while ISSR primers distinguished the S. lycopersicum esculentum accessions better than others.

The results indicated high genetic diversity among and within tomato species. According to genetic diversity features in both markers, it can be expected that the use of ISSR and SSR primers will be more effective for preparing genetic maps and studying population structure and/or accession grouping, respectively.