Genetic and Environmental Regulation of Flowering and Runnering in Strawberry

Cultivated strawberry (Fragaria × ananassa Duch.) is one of the most important berry crops worldwide. Its wild relative, woodland strawberry (Fragaria vesca L.) is also scientifically important, since recent development of molecular tools including genetic transformation methods, genetic maps and genome sequence is making it as one of the leading perennial model plants. Environmental regulation of strawberry reproductive development including flowering and vegetative reproduction through runners has been studied for almost hundred years and is known quite in detail. Most strawberries require short photoperiod and/or low temperature for the induction of flowering, whereas runnering is activated by opposite environmental signals. On the contrary, everbearing genotypes flower continu-ously in long day conditions. Some groundwork on characterization of molecular pathways controlling runnering and the induction of flowering has been done. In these studies, dozens of candidate flowering genes have been identified, the expression patterns for selected genes have been analyzed, and a marker gene for the induction of flowering has been identified. However, reports on detailed functions of the candidate genes are yet to come. Moreover, the role of gibberellin as a major signal regulating runnering, awaits further characteriza-tion. Two gene loci in F. vesca may provide keys to understand underlying regulatory pathways and are therefore major targets of further research. Runnering locus (RL) makes the difference between runnering/non-runnering phenotypes and different alleles of Seasonal flowering locus (SFL) cause seasonal and everbearing flowering habits. This review aims at summarizing the recent progress on molecular control of flowering and runnering in strawberry. _____________________________________________________________________________________________________________