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

Abstract

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.

Research Article Genetic divergence between onion populations derived from three different crossing methods

“…This observation suggested that the morphological characteristics due its dependence of environmental conditions are independent of their genetic relation. These observations are in agreement with González-Pérez et al (2015) who have reported the same on onion varieties grown in northwestern Spain. Table 2 shows the relative contribution of each trait to genetic diversity assessed according to the Sj statistic proposed by Singh (1981); bulbs/plot (28.32%), fruit fixation (13.12%) and seed weight/umbel (13.41%) together have contributed to 54.85% of total divergence between onion genotypes.…”

“…the onion genotypes narrow genetic base, González-Pérez et al (2015) also have observed divergence between groups of genotypes using UPGMA algorithms. As well, Tocher method have been satisfactorily applied to expose the divergence between groups of genotypes (Akter et al, 2015;Khosa and Dhatt, 2015;Rivera et al, 2016).…”

“…UPGMA dendrogram of 11 onion genotypes derived from three crossing methods (A1: self-fertilization of a plant, B2: intercrossing of two plants and C3: intercrossing of three plants), obtained by Euclidian distance Subtitle: Genotype 1, 2 and 3= GRxGR; Genotype 4, 5 and 6= 2; Genotype 13, 14 and 15= BUC; 1; Genotype 22, 23 and 24= GRxBOT 4; Genotype 31, 32 and 33= By examining, the UPGMA dendrogram in Figure 1 is possible observe that Groups II was made up by GRxBOT CRxBOT-1, IP-1 and BUC 2 and group VII by IP Pérez et al (2015) also have observed divergence between groups of genotypes using UPGMA algorithms. As well, Tocher method have been satisfactorily applied to expose the divergence between groups of genotypes (Akter et al, 2015;Khosa and Dhatt, 2015;Rivera et al, 2016).…”

Assessment of Genetic Diversity of the “Acquaviva Red Onion” (Allium cepa L.) Apulian Landrace

“…Biochemical analyses highlighted the sweetness of the 13 ARO populations, related to high soluble solid content and medium pungency, according to the sweet onion industry guidelines [31]. ARO bulbs were sweeter than those of the TRO and MCO landraces, and displayed a slightly higher pungency.…”

“…Thoroughly genetic and phenotypic characterization of agro-biodiversity is crucial to assure appropriate conservation of plant genetic resources and promote the use of specific genotypes in the value chain [30][31][32]. Simple sequence repeat (SSR) markers have been often chosen for mapping [33][34][35], DNA fingerprinting and cultivar discrimination [36][37][38], and reliable estimation of genetic variability within and among landraces [39][40][41][42], since they are locus specific, multi-allelic, codominantly inherited, highly reproducible, and suitable for automated genotyping.…”