A molecular marker set combining a retrotransposon insertion and SSR polymorphisms is useful for assessing diversity in Vitis

Molecular markers, based on DNA polymorphisms, are useful tools for identifying individuals, establishing phylogenetic relationships, managing collections of genetic material or assisting breeding. In the present study, we developed a marker set to differentiate Vitis species, grapevine varieties or clones belonging to the same variety. This novel marker set combines, in four PCR amplifications, the presence/absence of a remarkable retrotransposon, Tvv1-Δ3460, inserted at its single locus and the SSR polymorphism present within its two LTRs. By studying a collection of Vitaceaeaccessions, we showed the prevalence of two allelic forms of Tvv1-Δ3460 - one of which was partially truncated - in Vitis species. Out of the twenty-five studied Vitis species, the insertion of a Tvv1-Δ3460 element was detected in twenty, including Vitis vinifera. The homozygous vs heterozygous state of the element insertion was determined by amplifying the empty site. Additionally, each Tvv1-Δ3460 LTRs included a microsatellite sequence useful for designing markers based on LTR length. The LTR-SSR markers distinguished most of the fifty-two cultivars and revealed polymorphism within five of the seven varieties studied.

Validation of Microsatellite Markers of Pl Resistance Genes to Downy Mildew of Sunflower

Simple sequence repeats (SSR) polymorphism of 34 microsatellite loci (LG1, 8 and 13) was studied in lines carrying the downy mildew resistance genes Pl and lines with no Pl. The microsatellite loci ORS328 and ORS781 were selected as markers for genes Pl6 and Pl8 in lines HA 335 and QHP-1, respectively. Markers were identified for gene PlARG in RHA 419 and some accessions of H. argophyllus. The SSR markers ORS509, ORS605, ORS610, ORS1182 and ORS1039 were proven to reliably identify the parental line carrying PlARG gene, control and select the heterozygous F1 hybrids and identify homozygous genotypes in F2 generations. Obtained results indicate the necessity of validation of the markers in various germplasm pools and breeding collections. The SSR markers that are tightly linked to Pl6, Pl8, PlARG would be useful in the sunflower breeding. PlARG homozygous F2 segregants, developed and identified with marker assisted selection in this study, are recommended for further breeding as a new source of genetically determined resistance to downy mildew.