Multiplex SSR sets for variety identification in sunflower.

Germplasm characterization in crop species is essential for diversity conservation and utilization as well as for the protection of intellectual property. Due to their high polymorphism and reliability, microsatellites are considered the most suitable markers for those purposes; moreover, multiplex PCR analysis of SSR loci as a way to further increase informativeness and efficiency of testing, has already been reported for several species including sunflower. The discriminatory power of some SSR multiplex sets developed by other authors was here evaluated in order to establish a system for a rapid variety identification in sunflower. One hundred and twenty-one inbred lines of different origin, obtained from US, French and Italian public institutions, and representative of a wide range of genetic variability, were considered. All lines were male-fertile, and included both restorer and maintainer genotypes. In order to account for heterogeneity, for each accession DNA was extracted from five seedlings. Three six-plex combinations, with a total of eighteen SSR loci representing all chromosomes, were used to genotype all accessions. The number of alleles of individual markers ranged from 3 to 9, showing an heterozygosity (PIC) ranging from 0.34 to 0.83, with a mean of 0.65; the maximum average PIC value per set was 0.71. Each multiplex set allowed to distinguish accessions in more than 99% of the pairwise comparisons. The data indicate that this approach could represent an interesting tool for variety identification in sunflower.