Diversity Analysis and Genetic Mapping in Octoploid Strawberry (Strawberry × ananassa) Based on DArT Marker Platforms

Cultivated strawberry is an allo-octoploid crop with 28 pairs of chromosomes (2n = 8x = 56) for which no genome sequence is available. A wide number of strawberry cultivars are stored in ex situ germplasm collections world-wide and previous works have addressed the study of the extend of genetic diversity present within a limited number of these collections. The development of high throughput methods for genotyping will facilitate genome-wide characterizations of large accessions sets. We have developed two types of Diversity Array Technology (DArT) marker platforms for strawberry using a diverse set of cultivars. First, a microarray DArT was used to evaluate the genetic diversity of 63 strawberry cultivars that represent a wide range of variability based on phenotype, geographical origin and pedigrees. A total of 603 DArT markers were used to evaluate the diversity and structure of the population and the results compared to the same analyses using a set of 7 SSR markers selected from each of the seven chromosomes of F. vesca. Both clustering analyses revealed that DArT markers were more efficient in classifying the accessions in groups based on geographical and pedigree-based cues. Secondly, a DArTseq platform was used to develop a total of 18,772 SNP markers in the ‘232’ x ‘1392’ mapping population. After several filtering steps, 4,242 high quality markers were selected to saturate the previously developed ‘232’ x ‘1392’ linkage map. An integrated map comprising a total of 2,089 markers will be presented.