Genetic Diversity of a Germplasm Collection of Confectionery Sunflower Landraces from Spain

Native to North America, non-oilseed, confectionery sunflower (Helianthus annuus L.) has been traditionally cultivated in Spain since its introduction from the New World in the 16th century. This created great genetic diversity in the form of local landraces, whose characterization and conservation is of paramount importance. In this research, several seed and plant traits, as well as flowering time, were evaluated in a collection of 192 landraces of confectionery sunflower from Spain. Evaluation was conducted in Cordoba, Spain, in 2011, 2012, and 2013. The greatest variability was observed for hundred-seed weight (4.2119.68 g), plant height (65.00-361.67 cm), head diameter (9.00-31.00 cm), and days to flowering (64.31-103.00 d). Genetic diversity in the collection was also evaluated with a set of 52 simple sequence repeat (SSR) markers, which produced 167 alleles, with an average of 3.2 alleles per locus (from 2 to 5). The SSR markers disclosed moderate variability in the germplasm collection, with average Nei's expected heterozygosity of 0.29 (from 0.02 to 0.50). The analysis of the structure of the germplasm collection revealed the existence of two separated genetic pools, one of them widely distributed throughout the country and another one tracing back to a reduced area in the north of Cordoba Province, where accessions with a high level of membership in this group are still relatively common. Genetic diversity of this germplasm can be of use for widening the genetic base of cultivated sunflower.