Identification of SCAR markers linked to Rca2 anthracnose resistance gene and their assessment in strawberry germplasm

Abstract

Bulked segregant analysis combined with AFLPs was used to identify molecular markers linked to the Rca 2 gene conferring resistance to Colletotrichum acutatum pathogenicity group 2 which causes anthracnose in the octoploid strawberry Fragaria x ananassa. DNA bulks originating from a cross between the resistant cultivar 'Capitola' and the susceptible cultivar 'Pajaro' were screened with 110 EcoRI/M se IAFLP combinations. Four AFLP markers were found linked in coupling phase to Rca 2 with recombination percentages between 0% and 17.7%. Among the four markers linked to the resistance gene, two were converted into SCAR markers (STS-Rca 2417 and STS-Rca 2240) and screened in a large segregating population including 179 genotypes. The Rca 2 resistance gene was estimated to be 0.6 cM from STS-Rca 2417 and 2.8 cM from STS-Rca 2240. The presence/absence of the two SCAR markers was further studied in 43 cultivars of F. x ananassa, including 14 susceptible, 28 resistant, and one intermediate genotype. Results showed that 81.4% and 62.8% of the resistant/susceptible genotypes were correctly predicted by using STS-Rca 2417 and STS-Rca 2240, respectively. The 14 susceptible genotypes showed no amplification for either SCARs. These developed SCARs constitute new tools for indirect selection criteria of anthracnose resistance genotypes in strawberry breeding programs.

HaploSNP affinities and linkage map positions illuminate subgenome composition in the octoploid, cultivated strawberry ( Fragaria×ananassa )

“…The mapping studies performed in the cultivated strawberry have highlighted regions of extensive homozygosity in the genomes of modern F. ×ananassa cultivars attributed to repeated cycles of breeding and selection of specific loci, as well as rearrangements between the diploid and octoploid genomes [8,10]. Despite the molecular resources that have been developed for the cultivated strawberry, to date, only a few studies have reported the characterization of traits of economic importance [12][13][14][15][16], one of the main difficulties being finding sufficient numbers of markers to efficiently saturate QTL-containing regions of the genome.…”

A microsatellite linkage map for the cultivated strawberry (Fragaria × ananassa) suggests extensive regions of homozygosity in the genome that may have resulted from breeding and selection

“…Linkage mapping investigations in the cultivated strawberry have identified major genes and quantitative trait loci (QTL) for a number of agronomic traits, including disease resistance (Lerceteau-Kohler et al 2005), flowering habit (Sugimoto et al 2005;Weebadde et al 2008) and traits associated with fruit quality (Zorrilla-Fontanesi et al 2011a). However, these studies have often employed marker types that are not easily transferrable between mapping progenies, or traits have been identified in regions where no transferrable molecular marker loci have been located.…”

Functionalizing the Strawberry Genome—A Review

“…The first gains that will come from a sequenced genome will be from identification of molecular markers, easily traceable DNA patterns that associate with a trait of interest, complementing the current set available in strawberry (Whitaker, 2011). For example, it is possible to amplify a short piece of DNA in plants that tend to be resistant to anthracnose fruit rot, caused by Colletotrichum acutatum (Lerceteau-Kohler et al, 2005). Plants containing this fragment are resistant to the disease, whereas susceptible plants fail to permit amplification.…”