Abstract/Summary

Physiological and molecular genetic studies in the model plant Fragaria vesca were conducted to further understand the regulation of flowering in perennial plants. Different populations of F. vesca were collected from sites in the UK with different geographical and environmental conditions. These populations were propagated and studied in a common garden experiment at Reading University. Initial investigation into growth and floral emergence responses were carried out across the whole annual cycle and comparisons were made between three populations and with three different crown sizes. Further experiments were conducted on floral emergence using a single, large, crown size. Variation in floral initiation between populations was investigated and the specific effect of photoperiod on floral induction between representative northern and southern populations was tested in both outdoor and controlled environments. A new, simulated model was developed based on actual environmental measurements and used to test the responses of plants to a compressed annual cycle. Phylogenetic studies using barcoding genes to confirm species identification were carried out and the genetic sequence of a number of key floral genes was compared. Gene expression analysis was carried out for FvCONSTANS, FvFLOWERING LOCUS T1, FvTERMINAL FLOWER1 and FvSUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 in both inductive and non-inductive or selective conditions. Ecotypic variations were apparent between populations and these suggested a potential level of local adaptation. A representative northerly population demonstrated earlier floral induction in longer short day conditions compared to representative southerly populations. The critical day length for short day flowering, therefore, appeared to be longer in the northern populations. A high level of juvenility in seed propagated material made the comparison between these, and vegetative propagated plants, with a view to looking for differential heritability in adaptations, impractical. The new, compressed annual cycle model, based on actual environmental measurements, was run successfully. Differential timings of the peak in FvCO suggested that FvCO was responsive to a short day signal. The patterns of FvFTJ, FvTFLJ and FvSOCJ gene expression were in line with the expression models of floral induction in F. vesca and differences in expression appeared to support that northern and southern populations were differentially sensitive to the shortness of days, suggesting the potential of local adaptation.