Phenotyping and SSR markers as a tool for identification of duplicates in lettuce germplasm

In total, 117 individual samples from 39 accessions of Lactuca sativa were selected from the Czech national collection of lettuce with the aim to quantify and compare patterns of genetic and phenotypic variability within and among lettuce accessions and to propose a rapid, reliable and inexpensive method for verification of possible duplicates. We focused on phenotypic evaluation and SSR genotyping, and studied their ability to distinguish between individual accessions. Phenotypic data revealed that no two accessions shared the exactly same phenotype and no accession exhibited variability in the characters studied. Variability in SSR markers was very low as ten of twenty scorable SSR loci exhibited no variation and the remaining ten provided 48 alleles in total. Although neither phenotypic nor SSR data alone can serve as evidence for unambiguous duplicate confirmation, their combination increases the resolution power of the method considerably. The obtained data on cultivated lettuce indicate weak, but significant correlation (R-2 = 0.34, P = 0.01) between the two data sets.