Abstract
SummaryExtending the period of fruit production is a way to substantially increase crop yield in many fruit or ornamental species. In the cultivated octoploid strawberry (Fragaria × ananassa), the most consumed small fruit worldwide, fruit production season can be extended by selecting the perpetual flowering (PF) cultivars. This trait is of considerable interest to growers and to the food industry. Four homoeologous loci controlling a single trait can be expected in such a complex octoploid species. However, we recently showed that the PF trait is under the control of the single dominant FaPFRU locus (J. Exp. Bot., 2013, 64, 1837), making it potentially amenable to marker‐assisted selection (MAS). Here, we report the successful use of a strategy, based on a selective mapping using a reduced sample of individuals, to identify nine markers in close linkage to the FaPFRU allelic variant. Thus, this strategy can be used to fine map the target homoeologous loci in other complex polyploid crop species. Recombinant analysis further enabled us to reduce the locus to a region flanked by two markers, Bx083_206 and Bx215_131, corresponding to a 1.1 Mb region in the diploid F. vesca reference genome. This region comprises 234 genes, including 15 flowering associated genes. Among these, the FLOWERING LOCUS T (FT) is known to be a key activator of flowering. The close association between the PF trait and the FaPFRU flanking markers was validated using an additional segregating population and genetic resources. This study lays the foundation for effective and rapid breeding of PF strawberry cultivars by MAS.
Highlights
The length of the flowering period is a key trait in the development of high-yielding fruit or ornamental crops, because it determines flower number and, reproductive success
For the cultivated octoploid strawberry, the perpetual flowering (PF) trait has been shown to be controlled by the major QTL FaPFRU locus, which has been mapped to the female linkage group IVb (LGIVb-f) (Castro et al, 2015; Gaston et al, 2013)
The markers are subsequently used to redefine the boundaries for the locus of interest and to identify recombinants in larger populations that segregate for the trait
Summary
The length of the flowering period is a key trait in the development of high-yielding fruit or ornamental crops, because it determines flower number and, reproductive success. This trait depends on floral initiation, which is controlled by both environmental and genetic factors. Some perennials have the ability to flower more than once, thereby prolonging a favourable season, through a process called ‘remontancy’ or ‘perpetual flowering’ (PF) (Albani and Coupland, 2010; de Camacaro et al, 2002). A fine mapping of this region has been impeded by the octoploid status of the cultivated strawberry, and it remains a challenging task
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