An enhanced microsatellite map of diploid Fragaria

Abstract

A total of 45 microsatellites (SSRs) were developed for mapping in Fragaria. They included 31 newly isolated codominant genomic SSRs from F. nubicola and a further 14 SSRs, derived from an expressed sequence tagged library (EST-SSRs) of the cultivated strawberry, F. x ananassa. These, and an additional 64 previously characterised but unmapped SSRs and EST-SSRs, were scored in the diploid Fragaria interspecific F2 mapping population (FVxFN) derived from a cross between F. vesca 815 and F. nubicola 601. The cosegregation data of these 109 SSRs, and of 73 previously mapped molecular markers, were used to elaborate an enhanced linkage map. The map is composed of 182 molecular markers (175 microsatellites, six gene specific markers and one sequence-characterised amplified region) and spans 424 cM over seven linkage groups. The average marker spacing is 2.3 cM/marker and the map now contains just eight gaps longer than 10 cM. The transferability of the new SSR markers to the cultivated strawberry was demonstrated using eight cultivars. Because of the transferable nature of these markers, the map produced will provide a useful reference framework for the development of linkage maps of the cultivated strawberry and for the development of other key resources for Fragaria such as a physical map. In addition, the map now provides a framework upon which to place transferable markers, such as genes of known function, for comparative mapping purposes within Rosaceae.

Comparative Genetic Mapping Points to Different Sex Chromosomes in Sibling Species of Wild Strawberry (Fragaria)

“…DNA was diluted to 0.03 ng/ml with distilled deionized water for PCR reactions. Because we were interested in testing synteny, rather than creating a genetic map of the whole genome, we used 56 primer pairs for DNA markers (SSRs or genes) that have mapped either to the homeologous group (HG) in F. virginiana to which the protosex chromosome belongs (i.e., HG VI; Spigler et al 2010) or to the homeologous linkage group (LG) in a diploid interspecific cross (i.e., LG 6; Sargent et al 2006Sargent et al , 2008. PCR was performed using the Poor Man's PCR protocol (Schuelke 2000) as previously described (Spigler et al 2008).…”

“…For this comparison, we included only those DNA markers in the FV3FN LG 6 map (data kindly provided by D. Sargent) that were shared with both the F. chiloensis map in this study and the F. virginiana HG VI map from Spigler et al (2010). More stringent mapping parameters were used in both Sargent et al (2006) and Spigler et al (2010) to determine marker ordering. We therefore re-evaluated marker order of the F. chiloensis linkage group housing male and female function genes using JoinMap with similarly stringent parameters (a recombination threshold of 0.35, LOD threshold of 3.0, and jump threshold of 3.0).…”

The History Of Genome Mapping In Fragaria Spp.

“…In genetic mapping of diploid Fragaria plants, F2 population obtained from self-pollination or intercross of F1 has been used most frequently (Williamson et al 1995;Davis & Yu 1997;Deng & Davis 2001;Sargent et al 2004Sargent et al , 2006Sargent et al , 2007Sargent et al , 2008Sargent et al , 2011Ruiz-Rojas et al 2010;Illa et al 2011;Zorrilla-Fontanesi et al 2011b;Koskela et al 2012). However, some outline maps of F. vesca and F. viridis were elaborated on the basis of backcross population (BC), generated by crossing F1 individual(s) with inbred parent used in the initial cross (Nier et al 2006;Cekic et al 2001;Albani et al 2004).…”

“…The majority of segregating populations used for mapping genomes of Fragaria species contained 50 to 100 individuals Davis & Yu 1997;Haymes et al 1997;Sargent et al 2004Sargent et al , 2006Sargent et al , 2007Nier et al 2006;Rousseau-Gueutin et al 2008;Koskela et al 2012). Since more abundant progeny carries a greater number of meiotic recombination events, thus, it determines the resolution and accuracy of the linkage map more precisely (Paterson 1996), larger segregating populations of over 100 individuals were introduced in the study on F. vesca (Koskela et al 2012), F. virginiana and F. chiloensis (Spigler et al 2008Goldberg et al 2010) as well as F. × ananassa (Lerceteau-Köhler et al 2003, 2012Rousseau-Gueutin et al 2008Weebadde et al 2008;Sargent et al 2009Isobe et al 2012;Gaston et al 2013;van Dijk et al 2014).…”

“…However, markers described above have many drawbacks, such as low reliability and insufficient level of polymorphism (RAPD), dominant inheritance (RAPD, AFLP) (Paran & Michelmore 1993), and labourintensive data scoring (ISSR) (Cekic et al 2001). The usefulness of some of RAPD and AFLP markers for strawberry genome mapping increased after their conversion in SCARs (Sequenced Characterized Amplified Regions) Haymes et al 2000;Albani et al 2004;Sargent et al 2004Sargent et al , 2006Lerceteau-Köhler et al 2005).…”