Exploring genetic diversity and quality traits in a collection of onion (Allium cepa L) landraces from North-West Spain

Seventeen onion landraces from North-West Spain were evaluated using microsatellites markers. Eleven polymorphic markers identified 32 alleles in the whole collection, with an average of 2.9 alleles per locus. High values of observed (mean of 0.45) and expected heterozigosity (mean of 0.51) were detected for the majority of loci. Wright’s fixation index confirmed an excess of heterozygotes and a low level of inbreeding within the collection. Multivariate analyses revealed that Oimbra was the most distinctive genotype. The remaining 16 onion genotypes were in part assorted according to some morphological traits of bulbs. Pungency and solid soluble content highly varied among landraces and bulbs. Five landraces were classified as sweet, whereas 9 possessed medium pungency and 3 were recorded as pungent. This onion collection represents a useful source of genetic heterogeneity that might be exploited in breeding programs for the generation of new onion varieties that satisfy consumer demands.