Strawberry homologue of TERMINAL FLOWER 1 integrates photoperiod and temperature signals to inhibit flowering

Summary Photoperiod and temperature are major environmental signals affecting flowering in plants. Although molecular pathways mediating these signals have been well characterized in the annual model plant A rabidopsis , much less information is known in perennials. Many perennials including the woodland strawberry ( F ragaria vesca L .) are induced to flower in response to decreasing photoperiod and temperature in autumn and they flower following spring. We showed earlier that, in contrast with A rabidopsis , the photoperiodic induction of flowering in strawberry occurs in short days ( SD ) when the decrease in F v FT 1 ( FLOWERING LOCUS T ) and F v SOC 1 ( SUPPRESSOR OF THE OVEREXPRESSION OF CONSTANS 1 ) expression leads to lower m RNA levels of the floral repressor, F v TFL 1 ( TERMINAL FLOWER 1). By using transgenic lines and gene expression analyses, we show evidence that the temperature‐mediated changes in the F v TFL 1 m RNA expression set critical temperature limits for the photoperiodic flowering in strawberry. At temperatures below 13°C, low expression level of F v TFL 1 in both SD and long days ( LD ) allows flower induction to occur independently of the photoperiod. Rising temperature gradually increases F v TFL 1 mRNA levels under LD , and at temperatures above 13°C, SD is required for the flower induction that depends on the deactivation of F v SOC 1 and F v TFL 1 . However, an unknown transcriptional activator, which functions independently of F v SOC 1, enhances the expression of F v TFL 1 at 23°C preventing photoperiodic flowering. We suggest that the observed effect of the photoperiod × temperature interaction on F v TFL 1 m RNA expression may allow strawberry to induce flowers in correct time in different climates.