Inter Simple Sequence Repeat Markers Associated with Flowering Time Duration in the Chilean Strawberry (Fragaria chiloensis)

The flowering and fructification period of the Chilean strawberry (Fragaria chiloensis (L.) Duch.) is restricted to approximately 2 mo, which seriously limits the commercial development of the species. The objective of the current investigation was to identify Inter Simple Sequence Repeat (ISSR) polymorphisms associated with flowering duration in accessions of F. chiloensis. The flowering duration data related to 41 accessions obtained over 3 years were analyzed, and a set of 40 ISSR primers tested. Two clusters were obtained through the Partitioning Around Medoids algorithm, with 23 vs. 18 accessions, and 64.1 vs. 95.6 days of flowering, respectively. Flowering duration, between the two groups, was significantly different. The years also revealed a significant effect, on flowering duration, between the two groups. Ten of the ISSR primers tested revealed reproducible and consistent banding patterns, displaying a total of 106 putative loci, of which 79 were polymorphic. Three ISSR loci (811779, 844670, 841980) were identified owing to their significant contribution to the differentiation among the accessions. Similarly, three ISSR loci (811600, 8121180, 841980) exhibited a significant correlation with the flowering duration variation. Locus 841980, which presented the highest level of correlation with flowering duration, was isolated, cloned and sequenced, but it showed only a low level of homology with the relevant sequences published in the GenBank database. The identified loci showing high correlation with the flowering time could help build Quantitative Trait Loci (QTL) maps for selection and improvement programs in the Fragaria sp. genus or other related species.