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Simple sequence repeat markers linked to the everbearing flowering gene in long-day and day-neutral cultivars of the octoploid cultivated strawberry Fragaria × ananassa

Honjo, Masanori, Nunome, Tsukasa, Kataoka, Sono, Yano, Takayoshi, Hamano, Megumi, Yamazaki, Hiromichi, Yamamoto, Toshiya, Morishita, Masami, Yui, Susumu
Euphytica 2016 v.209 no.2 pp. 291-303
Fragaria ananassa, alleles, ancestry, crossing, dominant genes, everbearing cultivars, flowering, gene segregation, genotype, loci, microsatellite repeats, octaploidy, phenotype, plant breeding, progeny, strawberries
To identify markers closely linked to the everbearing gene in the octoploid cultivated strawberry Fragaria × ananassa, we conducted linkage analysis based on simple sequence repeat (SSR) polymorphisms. We analyzed F₁ populations from three crosses: ‘Sagahonoka’ × ‘Summer-berry’ (94 individuals), ‘Sagahonoka’ × ‘Ever-berry’ (137 individuals), and ‘Hecker’ × ‘Sagahonoka’ (177 individuals). ‘Sagahonoka’ is a June-bearing cultivar; ‘Summer-berry’ and ‘Ever-berry’ are everbearing cultivars classified as older everbearers with a long-day flowering response; ‘Hecker’ is a day-neutral cultivar having F. virginiana ssp. glauca in its ancestry. In these populations, the closest marker, FxaACA02I08C, was mapped at 1.1 cM (‘Summer-berry’ and ‘Hecker’) or 1.5 cM (‘Ever-berry’) from the everbearing gene. We detected correspondence between SSR allele segregation and the flowering habit: one allele was linked to the everbearing trait and the other one to the June-bearing trait. The concordance between the phenotype and marker genotype was more than 98 % in all three populations. These results indicate that the everbearing trait is regulated by a single dominant gene. We also conclude that the locus regulating the everbearing or June-bearing flowering habit is the same in long-day and day-neutral types. The identified markers will be useful for the selection of progeny of various everbearing cultivars.